AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 30, 1999

REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

SECURITIES AND EXCHANGE COMMISSION
WASHINGTON, DC 20549
------------------------

FORM S-3
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933
------------------------

EXCEL SWITCHING CORPORATION

(Exact name of Registrant as specified in its charter)

------------------------------

MASSACHUSETTS 04-2992806
(State or other jurisdiction (I.R.S. Employer
of incorporation or organization) Identification Number)

255 INDEPENDENCE DRIVE
HYANNIS, MA 02601
(508) 862-3000

(Address, including zip code, and telephone number,
including area code, of Registrant's principal executive offices)
------------------------------

ROBERT P. MADONNA
PRESIDENT AND CHIEF EXECUTIVE OFFICER
EXCEL SWITCHING CORPORATION
255 INDEPENDENCE DRIVE
HYANNIS, MASSACHUSETTS 02601TEL (508) 862-3000

(Name, address, including zip code, and telephone number,
including area code, of agent for service)
------------------------------

COPIES OF ALL COMMUNICATIONS, INCLUDING ALL COMMUNICATIONS SENT TO THE AGENT FOR
SERVICE, SHOULD BE SENT TO:

CHRISTOPHER STAVROS, ESQ. JOHN HESSION, ESQ.
EXCEL SWITCHING CORPORATION TESTA, HURWITZ & THIBEAULT, LLP
255 Independence Drive Oliver Street Tower, 125 High Street
Hyannis, Massachusetts 02601 Boston, Massachusetts 02110
(508) 862-3000 (617) 248-7000

APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after this Registration Statement becomes effective.

If the only securities being registered on this form are being offered
pursuant to dividend or interest reinvestment plans, please check the following
box. / /

If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. /X/

If this Form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /

If this Form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following. / /
--------------------------

CALCULATION OF REGISTRATION FEE

PROPOSED MAXIMUM PROPOSED MAXIMUM AMOUNT OF
TITLE OF EACH CLASS OF SECURITIES TO BE AMOUNT TO BE OFFERING PRICE PER AGGREGATE OFFERING REGISTRATION FEE
REGISTERED REGISTERED SHARE (1) PRICE (1) (2)

Common Stock, $.01 par value per share............ 924,458 $35.90625 $33,193,820 $9,227.88

(1) The price of $35.90625 per share, which is the average of the high and low
prices of the Common Stock of the Registrant reported on the Nasdaq National
Market on August 25, 1999, is set forth solely for purposes of calculating
the filing fee pursuant to Rule 457 of the Securities Act of 1933, as
amended.

(2) Calculated pursuant to Section 6(b) of the Securities Act of 1933.

EXCEL HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY
BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL EXCEL SHALL FILE A FURTHER
AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT SHALL
THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF THE SECURITIES
ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH
DATE AS THE COMMISSION, ACTING PURSUANT TO SECTION 8(A), MAY DETERMINE.

- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

SUBJECT TO COMPLETION, DATED AUGUST 30, 1999
THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY
NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE
SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER
TO SELL SECURITIES, AND IT IS NOT SOLICITING OFFERS TO BUY THESE SECURITIES IN
ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

EXCEL SWITCHING CORPORATION

924,458 SHARES

COMMON STOCK

This prospectus is offering 924,458 shares of our common stock for sale by
certain selling stockholders. These selling shareholders acquired their stock in
connection with our acquisition of RAScom, Inc. completed on May 10, 1999.
RAScom is now a wholly owned subsidiary of Excel.

We are receiving no proceeds from the sale of the shares offered for sale
hereunder. We have agreed to pay the expenses associated with registering these
shares but are not paying the expenses incurred by individual selling
stockholders. We may suspend the use of this prospectus during periods of time
if there then exists material, non-public information relating to Excel that, in
our reasonable opinion, would not be appropriate for disclosure.

Excel's common stock is traded on the Nasdaq National Market under the
symbol "XLSW." The last reported sale price of the common stock on the Nasdaq
National Market on August 25, 1999 was $36.75 per share.

------------------------

INVESTING IN THE COMMON STOCK INVOLVES RISKS.
SEE "RISK FACTORS" BEGINNING ON PAGE 3.

------------------------

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED THESE SECURITIES, OR DETERMINED IF THIS
PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

The date of this prospectus is August , 1999.

YOU SHOULD RELY ONLY ON THE INFORMATION CONTAINED HEREIN OR SPECIFICALLY
INCORPORATED BY REFERENCE IN THIS PROSPECTUS. WE HAVE NOT AUTHORIZED ANYONE TO
PROVIDE YOU WITH INFORMATION DIFFERENT FROM THAT CONTAINED IN THIS PROSPECTUS.
THE SELLING STOCKHOLDERS ARE OFFERING TO SELL, AND SEEKING OFFERS TO BUY, SHARES
OF COMMON STOCK ONLY IN JURISDICTIONS WHERE OFFERS AND SALES ARE PERMITTED. THE
INFORMATION CONTAINED IN THIS PROSPECTUS IS ACCURATE ONLY AS OF THE DATE OF THIS
PROSPECTUS, REGARDLESS OF THE TIME OF DELIVERY OF THIS PROSPECTUS OR OF ANY SALE
OF THE COMMON STOCK.

------------------------

TABLE OF CONTENTS

PAGE
---------

Summary of the Offering and the Company................................................................... 1
Risk Factors.............................................................................................. 3
Use of Proceeds........................................................................................... 11
Selling Stockholders...................................................................................... 12
Plan of Distribution...................................................................................... 17
Legal Matters............................................................................................. 18
Experts................................................................................................... 18
Where You Can Find More Information....................................................................... 18

------------------------

SUMMARY OF THE OFFERING AND THE COMPANY

Excel Switching Corporation is a leading provider of open switching
platforms for telecommunications networks worldwide. We develop, manufacture,
market and support a family of open, programmable, carrier-class switches that
address the complex enhanced services and wireless and wireline infrastructure
needs of network providers. Our products offer network providers the flexibility
to address multiple market applications and the scalability to deploy a variety
of system capacities. Our programmable switching platforms enable network
providers to deliver improved networking functionality at a lower cost than
purchasing, upgrading or reprogramming traditional, closed, central office
switches. Our products are currently deployed in telecommunications networks
throughout the world.

We offer a family of programmable switching platforms that are designed with
distributed architecture and open software to maximize performance and provide
multiple levels of programmability and redundancy. Our open switching platforms
integrate with a wide variety of host computer systems, operating systems and
application development environments. Our product family scales from
approximately 100 to 30,720 ports. Using our patented Programmable Protocol
Language ("PPL"), application developers can customize the switching software to
their unique requirements, allowing them to introduce new services and
applications rapidly. As customer requirements evolve, our platform can be
upgraded without extensive and complex programming changes to the underlying
software.

We sell to a variety of customers in the worldwide telecommunications
market. Our customers integrate our open, programmable switching platforms with
their product offerings to address a variety of market applications for network
providers, ranging from enhanced services such as voice messaging, one number
services and prepaid debit cards, to wireless and wireline infrastructure
services such as tandem, end-office, mobile switching centers, intelligent base
station controllers and wireless local loop.

Our products and technology are contained within the framework of Open
Network Expansion Architecture ("ONE Architecture-TM-") which was introduced in
February 1998. Our ONE Architecture provides an open, scalable and
cost-effective solution for the telecommunication needs of network providers.
ONE Architecture encompasses our existing family of switching products and
related embedded software technologies.

On August 17, 1999, we entered into an agreement with Lucent Technologies,
Inc. pursuant to which we agreed to be merged with and into a wholly owned
subsidiary of Lucent. Excel will survive the merger as a wholly owned subsidiary
of Lucent.

Consummation of the merger is subject to the satisfaction of various
customary conditions, including, among other things,

- approval of the merger by the stockholders of Excel

- expiration or early termination of the waiting period required under the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended

- the receipt by Lucent of a letter from Price Waterhouse Coopers LLP that
concurs with the conclusion of Lucent's management that no condition
exists that would preclude the merger from being accounted for as a
pooling of interests

- the receipt by Excel of a letter from Arthur Andersen LLP that concurs
with the conclusion of Excel's management that no condition exists that
would preclude the merger from being accounted for as a pooling of
interests

Upon consummation of the merger with Lucent, each share of Excel common
stock then issued and outstanding will be converted automatically into the right
to receive 0.558 shares of Lucent common stock. Please see the Report on Form
8-K dated August 17, 1999 and filed with the Commission on August 26, 1999 and
which is incorporated by reference in this prospectus. For the list of documents
incorporated by reference herein, see "Where You Can Find More Information" on
page 18 of this prospectus.

Our principal executive offices are located at 255 Independence Drive,
Hyannis, Massachusetts, 02601 and our telephone number is (508) 862-3000. As
used in this prospectus, "we," "us," "our" and "Excel" refer to Excel Switching
Corporation, a Massachusetts corporation, and its wholly owned subsidiaries.

RISK FACTORS

YOU SHOULD CAREFULLY CONSIDER THE FOLLOWING FACTORS AND OTHER INFORMATION IN
THIS PROSPECTUS BEFORE DECIDING TO INVEST IN SHARES OF COMMON STOCK. ADDITIONAL
RISKS AND UNCERTAINTIES THAT WE ARE UNAWARE OF OR THAT WE CURRENTLY DEEM
IMMATERIAL MAY ALSO BECOME IMPORTANT FACTORS THAT MAY AFFECT EXCEL.

IF ANY OF THE FOLLOWING RISKS OCCUR, OUR BUSINESS, FINANCIAL CONDITION OR
RESULTS OF OPERATIONS COULD BE MATERIALLY HARMED. IN THAT CASE, THE TRADING
PRICE OF OUR COMMON STOCK COULD DECLINE DRAMATICALLY, AND YOU MAY LOSE ALL OR
PART OF YOUR INVESTMENT.

THIS PROSPECTUS ALSO CONTAINS FORWARD-LOOKING STATEMENTS THAT INVOLVE RISKS
AND UNCERTAINTIES. OUR ACTUAL RESULTS COULD DIFFER MATERIALLY FROM THOSE
ANTICIPATED IN THESE FORWARD- LOOKING STATEMENTS AS A RESULT OF CERTAIN FACTORS,
INCLUDING THE RISKS FACED BY US DESCRIBED BELOW AND ELSEWHERE IN THIS
PROSPECTUS.

OUR OPERATING RESULTS MAY FLUCTUATE SIGNIFICANTLY BECAUSE SALES OF OUR
PRODUCTS ARE SUBJECT TO DEMAND AND TIMING CONSIDERATIONS OF OUR CUSTOMERS.

We have experienced significant variations in our operating results on a
quarterly and annual basis and anticipate possible fluctuations in our future
operating results. Our revenues and operating results have fluctuated
considerably from quarter to quarter, typically with higher product orders and
revenues in the fourth quarter, and lower revenues in the first quarter. Also,
we have historically recognized a large portion of our revenues from sales
booked and shipped in the last month of each quarter. Because we operate with
little backlog, quarterly revenues depend significantly on orders booked and
shipped in that quarter and on sales by our customers to end users. In addition,
our expense levels are relatively fixed and are based in significant part, on
expectations of future revenue. Consequently, if revenue levels fall below
expectations, expense levels could be disproportionately high as a percentage of
revenues.

If any of these fluctuations or variations occur, our operating results may
fall below analyst expectations. As a result, the market price of our common
stock may decline significantly.

Our quarterly and annual operating results may also vary due to a number of
factors including:

- the timing and size of product orders;

- the commercial success of our products;

- our ability to introduce new products and technologies on a timely basis;

- the financial stability of our major customers;

- the timing of new product introductions or announcements by us or our
competitors;

- the availability of adequate supplies of key components and assemblies and
the adequacy of third-party manufacturing capabilities;

- the seasonality of the placement of customer orders;

- the timing and nature of selling and marketing expenses such as tradeshows
and advertising campaigns;

- the timing of development expenditures and personnel changes;

- the publication of opinions about us and our products, or our competitors
or their products, by industry analysts;

- customer order deferrals in anticipation of product enhancements or new
product offerings by us or our competitors; and

- customer cancellation of orders and the gain or loss of significant
customers, including those due to industry combinations.

OUR REVENUES DEPEND UPON SALES TO A RELATIVELY SMALL NUMBER OF CUSTOMERS AND
WE ARE SUSCEPTIBLE TO CHANGES IN OUR RELATIONSHIPS WITH SUCH CUSTOMERS.

Although our customer base continues to broaden, our operating results in
any given period continue to depend to a significant extent upon sales to a
small number of customers, and revenues from our largest customers may
significantly fluctuate from period to period. None of our customers has entered
into a long-term supply agreement with minimum purchase requirements. There can
be no guarantee that our principal customers will continue to purchase our
products at current levels, if at all, or whether we will be able to replace
such purchases with sales to other customers. The loss of one or more major
customers could have a negative effect on our business, financial condition and
operating results.

WE FACE SIGNIFICANT COMPETITION FROM OTHER TELECOMMUNICATION EQUIPMENT
COMPANIES.

The market for telecommunications products is highly competitive and subject
to rapid technological change. We compete directly and indirectly with other
manufacturers of programmable switches, including large, well-established switch
and telecommunications equipment manufacturers and, to a lesser extent, systems
integrators and application developers whose switches are based on PC card-level
products. Many of our current and potential competitors have significantly
greater financial, selling and marketing, technical, manufacturing and other
resources.

Due to the rapidly evolving markets in which we compete, additional
competitors with significant market presence and financial resources could
easily compete against us in one or more market segments. Increased competition
could result in price reductions and loss of market share which would negatively
impact our business, financial condition and results of operations. Although we
believe that we have certain technological and other advantages over our
competitors, realizing and maintaining such advantages will require a continued
high level of investment by us in research and product development, marketing
and customer service and support. It is not certain that we will have sufficient
resources to continue to make such investments or that we will be able to make
the technological advances necessary to compete successfully with our existing
or new competitors.

YEAR 2000 ERRORS COULD CAUSE OUR PRODUCTS AND THOSE OF OUR CUSTOMERS TO
MALFUNCTION.

Many existing computer systems and software products do not properly
recognize dates after December 31, 1999. The Year 2000 problem could result in
miscalculations, data corruption, system failures or disruptions of operations.
We have implemented a Year 2000 compliance program designed to ensure that our
computer systems and applications will function properly beyond 1999, and expect
our date conversion programs to be completed on a timely basis. However, there
can be no assurance that Year 2000 errors or defects will not be discovered in
our systems or that we will be able to successfully remedy any problems that are
discovered.

If key systems were to fail as a result of Year 2000 problems, we could
incur substantial costs and disruption of our business, which would potentially
have a negative impact on our business and operating results. In addition, Year
2000 errors or defects in the products or internal systems of our suppliers
could negatively impact our business, financial condition and operating results.

WE DEPEND ON RELATIONSHIPS WITH CUSTOMERS AND THEIR ABILITY TO INTEGRATE OUR
PRODUCTS.

We sell a significant amount of our products to, and maintain strategic
relationships with, application developers, original equipment manufacturers and
systems integrators which incorporate our products into their services and
product offerings. As a result, our product sales are in part dependant upon the
continued market acceptance of the service and product offerings of our
customers. Also, the delay or failure of a customer's application development
program incorporating our products could delay or prevent expected sales of our
products. Although we maintain contractual relationships with many of our
customers, these contracts do not provide for minimum purchase requirements or
require the exclusive purchase of our products. Lack of market acceptance of the
service and product offerings of our customers

or a customer's decision to market products manufactured by a competitor would
have a negative effect on our business, financial condition and operating
results.

Additionally, selling through indirect channels may limit our information
concerning the volume of products sold by our customers to end-users, and our
ability to forecast revenues accurately, evaluate end-user satisfaction and
recognize emerging end-user requirements may be hindered accordingly.

SALES PURSUANT TO OUR LEASE FINANCING PROGRAM MAY NOT BE ON COMPETITIVE
TERMS AND EXPOSE THE COMPANY TO SIGNIFICANT POTENTIAL RECOURSE OBLIGATIONS.

In March 1999, we entered into an arrangement with a leasing entity to
enable our customers to finance the purchase of our equipment. Under the terms
of this arrangement, as amended, we have a recourse obligation in the amount of
the greater of $1,000,000 or 20% of the aggregate net book value of annual
equipment sales financed. In addition, we have a 100% recourse obligation for
contracts funded for customers with certain credit ratings, as determined by the
leasing entity. It is not certain that the financing alternative provided by
this relationship will be on terms that are competitive with the financial
offerings of our competitors. It is not certain we will continue to offer such
financing alternatives in the future. Since we are obligated to guarantee the
payments to the leasing entity, the default by one or more customers of their
payment obligations to the leasing entity under this program may have a negative
impact on our business, financial condition and operating results. In addition,
such default may have an adverse impact on our ability to continue to offer such
alternative financing to our customers.

WE DEPEND HEAVILY ON SINGLE AND SOLE SOURCE SUPPLIERS AND THIRD-PARTY
MANUFACTURERS AND ARE THEREFORE DEPENDENT ON THEIR FUTURE VIABILITY.

We currently purchase many key components from single or sole source
suppliers. If the components from such suppliers should become unavailable for
any reason, we could experience delays in our product shipments or we may be
required to redesign our products or stop providing such applications with our
products. Because we do not have long-term contracts with our suppliers, it is
uncertain whether they will continue to be able to produce these components or
to meet our requirements. Any significant interruption in the supply, or
degradation in the quality, of any such component could cause sales to decrease,
market share to be lost permanently, and could result in significant expenses to
obtain alternative sources of supply with the necessary attributes.

Although we generally require our customers to submit quarterly forecasts of
their needs, our customers frequently require rapid delivery after the placement
of a purchase order. Because we do not maintain significant component
inventories, a delay in a shipment by a supplier could lead to lost sales. If
orders vary from forecasts, we may experience excess or inadequate inventory of
certain materials and components. Any shortages could result in delays of
fulfillment of customer orders. Such delays and shortages could have a negative
effect on our business, financial condition and operating results.

THE EVOLVING MARKET FOR TELECOMMUNICATIONS SERVICES PRODUCES RAPID
TECHNOLOGICAL CHANGE AND COMPETITORS MAY ADAPT MORE QUICKLY TO THESE CHANGES.

The global telecommunications marketplace is evolving and it is difficult to
predict its potential size or future growth rate. Our future success depends on
continued growth in the market for telecommunications services.
Telecommunications applications and infrastructure needs may emerge for which
our products are not designed and if this market grows more slowly or in a
different direction than we currently anticipate, our business, financial
condition and operating results could be negatively affected.

The telecommunications equipment market is also characterized by rapid
change, evolving industry standards and emerging technologies. Our position in
this market could rapidly erode due to unforeseen changes in competing products.
Our growth and future results depend in part on our ability to respond to these
changes by enhancing our existing products and developing and introducing new
products and features. Failure on our part to respond to rapidly changing
technologies could negatively impact our business, financial condition and
operating results.

WE ARE SUSCEPTIBLE TO RISKS RELATING TO THE DISRUPTION OF OUR ONGOING
BUSINESS AND THE DIVERSION OF MANAGEMENT RESOURCES IN CONNECTION WITH RECENT AND
FUTURE ACQUISITIONS.

In the past, we have pursued the acquisition of other companies, assets,
products and technologies. Acquisitions may disrupt our ongoing business and
distract management. Acquisitions also involve many operating risks that could
negatively impact our operating results, and we may lack experience in the
businesses we acquire. Because we have limited experience integrating acquired
companies and technologies into our operations, we may not be able to manage
present and future acquisitions successfully or integrate the operations,
products or personnel gained through such acquisitions without a negative effect
on our business, financial condition and operating results.

WE MAY EXPERIENCE DIFFICULTY INTEGRATING RECENT ACQUISITIONS.

Having recently acquired assets, products and technology from companies such
as RAScom, Inc., Phoenix Wireless Technologies, Inc. and Intercall
Communications & Consulting, Inc., the successful integration of the operations,
personnel and product lines of these companies is important to the future
financial performance of the combined enterprise. Realization of potential
benefits from these acquisitions may not occur unless the products, technologies
and personnel of these acquisitions are successfully combined and integrated
with our operations in a timely and efficient manner. The diversion of the
attention of management, and any difficulties encountered in the transition
process, could have a negative impact on the revenues, financial condition and
operating results of the combined enterprise. We may not be able to successfully
integrate these companies and their services and products into our operations.
The inability of management to successfully integrate the operations of the
companies could have a negative effect upon our business, financial condition
and operating results.

WE MAY EXPERIENCE DIFFICULTY OF INTEGRATING THE PRODUCT LINES OF RECENT
ACQUISITIONS.

As part of our product plans following our recent acquisitions, we expect to
be integrating the products of our recent acquisitions with our programmable
switching technology for the enhanced services and wireless and infrastructure
markets, as well as for small- and medium-sized Internet Service Providers. The
integration of these product offerings can be costly, and result in
unanticipated delays or difficulties with product integration, and require
further development expenses and further expenditures for sales and marketing
campaigns associated with advertising the new, complementary product offerings.
There is no assurance that development teams can be successfully assimilated
with our engineering personnel, or that engineering personnel will continue to
remain with us following the acquisition. We also have no assurance that our
existing customers will purchase the new product lines, once integrated, or that
we will be able to attract new customers with the added product capabilities.
While our management believes the combined technologies enhance our existing
product offerings and expand our addressable markets, delays or difficulties
associated with this product integration or the loss of key engineering
personnel could have a negative effect on our business and operating results.

WE ARE SUSCEPTIBLE TO UNCERTAINTIES RELATING TO THE INTEGRATION OF
OPERATIONS WITH THOSE OF RECENT ACQUISITIONS.

We believe that recent acquisitions will result in long-term strategic
benefits. However, the realization of these benefits will depend on whether our
management can integrate our operations with those of the acquisitions in an
efficient and effective manner. Among other things, we must integrate our
respective products, technologies, distribution channels and key personnel.
Furthermore, we must coordinate our collective sales, marketing and research and
development efforts. The difficulties of integrating recent acquisitions may be
increased by the need to coordinate organizations with distinct cultures and
widely dispersed operations. The effective integration of the various operations
will depend on our ability to attract and retain key management, sales,
marketing and research and development personnel. The integration of operations
following the acquisition will require significant attention of management and
thus may distract attention from our other day-to-day operations.

WE NEED TO INTEGRATE AND RETAIN KEY EMPLOYEES OF RECENT ACQUISITIONS.

The successful integration of our recent acquisitions is dependent on the
retention and integration of the key management, sales, marketing, engineering
and other technical employees of the acquired companies. In the period since the
completion of the RAScom acquisition, some key personnel have left. Competition
for qualified personnel in the telecommunications industry is very intense.
Competitors can offer compensation packages that include equity compensation and
other incentives that make it difficult for us to compete in hiring qualified
personnel. In addition these competitors may recruit other key employees during
the integration phase following these acquisitions. The loss of these key
personnel and the failure to hire qualified replacements could have a negative
effect on our business, financial condition and operating results.

OUR RECENTLY ANNOUNCED MERGER WITH LUCENT TECHNOLOGIES, INC. MAY NOT BE
CONSUMMATED.

On August 17, 1999, we signed a definitive agreement with Lucent
Technologies, Inc. pursuant to which Excel will be merged with and into a wholly
owned subsidiary of Lucent. Upon completion of the merger, Excel will survive as
a wholly owned subsidiary of Lucent. Upon consummation of the merger with
Lucent, each share of Excel common stock then issued and outstanding will be
converted automatically into the right to receive 0.558 shares of Lucent common
stock.

There is no guarantee that the merger with Lucent will be consummated, or if
it is consummated, there is no guarantee that it will be on the same terms as
currently negotiated. Several conditions must be met in order for the merger to
be consummated. These conditions include, among others, the following:

- approval of the merger by the stockholders of Excel

- expiration or early termination of the waiting period required under the
Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended

There is no guarantee that any of these conditions will be met. The failure
to meet any one of the conditions precedent to the consummation of the merger
may delay consummation of the merger or may cause its termination. The failure
to consummate the merger would have a negative affect on our business, financial
condition and operating results and will result in a dramatic decrease in the
trading price of our stock.

In addition, the failure to consummate the merger in a timely fashion would
delay expected product, personnel and technology integration and would have a
negative effect on our business, financial condition and operating results. Our
business may also be negatively effected as a result of (i) delays, reductions
or cancellations or changes in the terms or timing of product orders or product
implementations by our customers, (ii) attrition of our employees, (iii)
litigation brought or threatened against us, any of our principal stockholders
or a member of our Board of Directors, and (iv) the refusal by any of our
suppliers to continue to do business with us, each as a result of the proposed
merger with Lucent or the announcement of such proposed merger.

MANY OF OUR CUSTOMERS AND SUPPLIERS ARE COMPETITORS OF LUCENT AND MAY
TERMINATE THEIR RELATIONSHIP WITH US PRIOR TO CONSUMMATION OF THE MERGER.

Many of our customers and suppliers are also competitors of Lucent. Prior to
consummation of the merger, such customers and suppliers may terminate their
relationship with us. The loss of such customers and suppliers and the failure
to replace them may have a negative effect on our business, financial condition
and results of operations.

OUR MANAGEMENT RESOURCES MAY BE DIVERTED IN CONSUMMATING THE MERGER AND
INTEGRATING OPERATIONS.

Consummation of the merger and the integration of our products, personnel
and technology with Lucent will require the devotion of significant management
resources. As our management team has limited experience with consummating a
merger of this kind and integrating the operations of two companies, significant
additional resources may have to be devoted to such endeavors. The diversion of
management resources away from the day to day operations of the business may
have a negative affect on our business, financial condition and results of
operations.

OUR TRADING PRICE NOW TRENDS WITH LUCENT'S TRADING PRICE AND AN ASSESSMENT
BY THE MARKET OF WHETHER THE MERGER WILL BE COMPLETED.

As each issued and outstanding share of Excel common stock is to be
exchanged into a fixed number of shares of Lucent common stock in connection
with the merger, our stock price trends directly with the trading price of
Lucent's common stock. The price of Lucent common stock may be affected by
factors different from those that may affect the price of our common stock. A
decline in the trading price of Lucent's common stock would have a negative
effect on our trading price and may have a negative effect on our business,
financial condition and results of operations. A decline in the trading price of
Lucent's common stock may also impact the consummation of the merger. Lucent's
trading price on the date of consummation of the merger may be less than it is
on the date of this prospectus. Factors that may affect both the trading price
of Lucent common stock and Excel common stock include the following:

- changes in the business, operations or prospects of Lucent

- market assessments of the likelihood that the merger will be completed

- the timing of the completion of the merger

- the prospects of post-merger operations

- regulatory considerations

- general market and economic conditions

OUR SALES TO END-USERS ARE SUBJECT TO A VARIETY OF RISKS DUE TO OUR LIMITED
EXPERIENCE IN DISTRIBUTING DIRECTLY TO END-USERS.

We intend to increase the volume of sales to end-users over the next several
periods. Although our products have historically been distributed through
indirect channels to end-users, we have limited experience in distributing
directly to and directly supporting end-users. Sales to end-users are subject to
a variety of risks, including increased costs to promote and market the
products; increased costs to install and integrate products and support the
customer base; increased warranty obligations and a longer sales cycle. Sales to
end-users may also involve significant acceptance, performance and other
milestone criteria, which may impact the timing of the revenue recognition. The
installation of a complete system involves the integration of our product with
various third-party equipment and applications. Difficulties or delays in
integration may result in delays in market acceptance and sales, diversion of
development and management resources, injury to our reputation or increased
service and warranty costs, any of which could have a negative affect on our
business, financial condition and operating results.

Sales to end-users may require us to provide additional third-party
components and software applications. The inability to obtain sufficient
supplies of these components and applications could result in delays or
reductions in product shipments which could negatively affect our business,
financial condition and operating results.

In order to meet the needs of network providers, we may be required to
further develop or enhance our existing product offerings or acquire additional
products and technologies from third parties. Such new

products or enhancements may require us to obtain additional technical
certification in telecommunications networks. Delays in product development and
certification could negatively impact our business, financial condition and
operating results.

WE DERIVE MOST OF OUR REVENUES FROM OUR CONCENTRATED PRODUCT FAMILY.

We currently derive substantially all of our revenues from our family of
open, programmable switching platforms. Any decrease in the overall level of
sales of our switching platforms, due to product developments by our competitors
or a decline in the demand for our products, could have a negative effect on our
business, financial condition and operating results.

WE MAY EXPERIENCE DIFFICULTIES IN THE DEVELOPMENT AND INTRODUCTION OF OUR
NEW PRODUCTS.

We intend to continue to invest in product and technology development, but
we may experience difficulties that could delay or prevent the successful
development, introduction or marketing of such new products and enhancements. It
is not known whether our new products and enhancements will adequately meet the
requirements of the marketplace and achieve market acceptance. Announcements of
currently planned or other new product offerings by us or our competitors may
cause customers to defer or cancel the purchase of our existing products. Any
inability on our part to develop new products or enhancements to existing
products on a timely basis, or the failure of such new products or enhancements
to achieve market acceptance, could have a negative impact on our business,
financial condition and operating results.

The development of new, technologically advanced products is a complex and
uncertain process requiring the accurate anticipation of technological and
market trends. The introduction of new or enhanced products also requires us to
manage successfully the transition from older products. It is not certain that
we will successfully develop, introduce or manage the transition to new
products. Furthermore, such new products may contain undetected or unresolved
errors when they are first released. Errors found in any new products or
upgrades after the commencement of commercial shipment could have a negative
impact on our business, financial condition and operating results.

SIGNIFICANT GROWTH AND EXPANSION PLACE SIGNIFICANT DEMANDS ON OUR MANAGEMENT
AND KEY PERSONNEL AND WILL REQUIRE US TO HIRE ADDITIONAL EMPLOYEES.

We have experienced growth in revenues and expansion of our operations which
have placed significant demands on our management, engineering staff and
facilities. We believe that further improvements in management and operational
controls are needed, and will continue to be needed, to manage any further
growth. Continued growth will also require us to hire more engineering, selling
and marketing and administrative personnel, expand customer management
information systems and improve our inventory management practices.

While we believe that our current and planned facilities are adequate to
meet our immediate needs, future growth may require us to obtain additional or
alternative facilities. Due to the limited supply of suitable additional or
alternative office and manufacturing space in the Cape Cod, Massachusetts area,
there can be no assurance that such space can be leased or acquired without the
need for substantial renovations. Relocation of any segment of our operation may
disrupt business and have a negative impact on our business, financial condition
and operating results. Additionally, the local permitting and variance
procedures for the renovation or construction of buildings in the Cape Cod area
is more onerous than similar procedures in metropolitan areas. Thus, we may be
required to devote significant resources in the future to the permitting and
renovation of additional facilities or in relocating some or all of our
facilities.

Our success depends to a significant degree upon the continuing
contributions of our key management, engineering, selling and marketing and
manufacturing personnel, with whom we do not have employment contracts. The loss
of the services of any key employee, the inability to attract or retain
qualified personnel in the future or delays in hiring required personnel could
have a negative impact on

our business, financial condition and operating results. We have at times
experienced, and continue to experience, difficulty in recruiting qualified
personnel, and it is not certain we will be able to attract and retain the
necessary personnel in the future.

OUR SUCCESS DEPENDS ON OUR ABILITY TO EXPAND AND MANAGE OUR INTERNATIONAL
OPERATIONS.

Direct sales attributable to customers located outside of the United States
represented approximately 8% and 11% of our revenues in 1997 and 1998,
respectively. We intend to further expand our operations outside the United
States and enter additional international markets, which will require
significant management attention and financial resources. International sales
are subject to a variety of risks, including:

- difficulties in establishing and managing our relationships with
international distributors

- difficulties in servicing and supporting products sold outside of the
United States

- difficulties in translating products and related materials into foreign
languages

- difficulties in collecting accounts receivable

- staffing and managing personnel

- difficulties in enforcing intellectual property rights abroad

- fluctuations in exchange rates

- tariffs and trade barriers

- changes in import/export duties and quotas

- political, social, and economic conditions in international markets

- seasonal fluctuations in international sales

These factors may have a negative effect on our future international sales
and, consequently, on our business, financial condition and operating results.

OUR SALES CYCLE IS LENGTHY AND MAY BE SUBJECT TO UNCONTROLLABLE DELAYS.

The time between the date of initial contact with a potential customer and
large-scale commercialization of a new customer application or system based on
our products is often lengthy, typically ranging from 12 to 24 months or more,
and is subject to delays over which we have little or no control. Although we
attempt to develop our products in a timely manner so as to facilitate the time
to market of our customers' products, the timing of delivery of new customer
applications or services based on our products is primarily dependent on such
customer's own internal development program. Delays can also be caused by late
deliveries by other vendors, changes in implementation priorities and slower
than anticipated growth in demand for the services that our products support. A
delay in, or cancellation of, the sale of our products could have a negative
effect on our business, financial condition and operating results and cause our
operating results to vary significantly from quarter to quarter.

OUR PROPRIETARY RIGHTS ARE PROTECTED BY MEASURES THAT MAY BE INADEQUATE.

We generally rely upon patent, copyright, trademark and trade secret laws,
confidentiality procedures and contractual restrictions to establish and protect
our proprietary rights. These protections may be inadequate, and our competitors
may independently develop or duplicate technologies that are similar to our
technology. In addition, the laws of certain countries in which our products are
sold do not protect our products and intellectual property rights to the same
extent as the laws of the United States.

It is possible that third parties will assert infringement or
misappropriation claims against us in the future with respect to current or
future products. Litigation to defend and enforce our intellectual property

rights could result in substantial costs and diversion of resources and could
have a negative impact on our business, financial condition and operating
results, regardless of the outcome of such litigation. Despite our efforts to
safeguard and maintain our proprietary rights, we may not be successful in doing
so and the steps taken by us in this regard may not be adequate to deter
misappropriation or independent third-party development of our technology or
prevent an unauthorized third party from copying or otherwise obtaining and
using our products or technology.

WE MUST COMPLY WITH A SIGNIFICANT NUMBER OF REGULATIONS AND EVOLVING
INDUSTRY STANDARDS.

The market for our products is characterized by the need to meet a
significant number of evolving communications regulations and standards, both in
the United States and abroad. The failure of our products to comply, or delays
in compliance, with the various existing and evolving industry regulations and
standards could delay the introductions of our products. Furthermore, the
enactment of new laws or regulations, or changes in the interpretation of
existing laws or regulations could negatively affect our customers, and thereby
negatively affect our business, financial condition and operating results.

USE OF PROCEEDS

Excel will not receive any of the proceeds from the sale of any of the
shares being offered and sold by the selling stockholders pursuant to this
prospectus. See "Selling Stockholders" and "Plan of Distribution". The principal
purpose of this offering is to effect an orderly disposition of the shares of
common stock of Excel being offered and sold from time to time by the selling
stockholders.

SELLING STOCKHOLDERS

The following table sets forth as of July 9, 1999, the following:

(i) the name of each selling stockholder,

(ii) the number of shares of common stock and the percentage of outstanding
common stock beneficially owned by each such selling stockholder before
this offering,

(iii) the number of shares that each selling stockholder may offer and sell
pursuant to this prospectus, and

(iv) the number of shares of common stock and the percentage of outstanding
common stock beneficially owned by each such selling stockholder after
this offering.

The shares registered pursuant to this prospectus may be offered from time
to time by any of the selling stockholders named below or by those individuals
and entities to which they may transfer or distribute the shares. See "Plan of
Distribution."

Except as described below, each of the selling stockholders has sole voting
and investment power with respect to the shares beneficially owned by them. In
addition, except as described below, none of the selling stockholders has had
any material relationship with Excel or any of its predecessors or affiliates
within the past three years. This information was compiled solely from
representations received from each of the selling stockholders.

Since each selling stockholder may sell all, some or none of their shares
registered under this prospectus, no estimate can be made of the aggregate
number or percentage of shares of common stock that each selling stockholder
will beneficially own upon completion of this offering. Thus, we have assumed
that the selling stockholders will sell all of the shares of common stock
registered for them under this prospectus.

In calculating the percentage of shares beneficially owned by each selling
stockholder after completion of the offering, we have based our calculations on
the fact that as of August 17, 1999, a total of 36,946,110 shares of common
stock were outstanding.

NUMBER OF
SHARES BENEFICIALLY NUMBER OF SHARES
OWNED PRIOR TO BENEFICIALLY OWNED
OFFERING (A) NUMBER OF AFTER OFFERING (A)
------------------- SHARES ----------------------
NAME NUMBER PERCENT OFFERED NUMBER PERCENT
- ----------------------------------- -------- ------ --------- -------- -----------

Philip Arrigo...................... 129(1) * 116 13 *
Frances Arrigo

Kathy Barrie....................... 160(2) * 13 147 *

Michael Barza...................... 7,684 * 6,916 768 *

Jeffery Basile (3)................. 3,484(4) * 3,136 348 *

Margo Bik.......................... 2,871(5) * 2,584 287 *
Nicholas Bik

Chris Carroll...................... 888 * 869 19 *

R. Stephen Cheheyl................. 2,740 * 2,466 274 *

Steven Churchill................... 155 * 155 0 *

Arnold Denton...................... 82 * 76 6 *

Richard Desmarais.................. 259 * 259 0 *

Geoffrey Devine.................... 2,656 * 2,390 266 *

C.W. Dick.......................... 182,683(6) * 1,627 181,056 *

Kevin Dick......................... 259 * 233 26 *

Daniel Donahue..................... 374 * 374 0 *

Peter Dumas........................ 445 * 445 0 *

Gerald Friesen..................... 4,974 * 4,477 497 *

Patrick Gablosky................... 60 * 60 0 *

Aaron Galvin (7)................... 16,459(8) * 14,453 2,006 *
Frayda Galvin

Mark Galvin (9).................... 179,908(10) * 159,758 20,150 *

Joseph C. Genovese (11)............ 4,324 * 3,892 432 *

Stefan Gieseler (12)............... 3,969(13) * 1,894 2,075 *

Antonio Gonzalez................... 22 * 22 0 *

Robert Grochmal.................... 445 * 400 45 *

Robert Grochmal.................... 667(14) * 600 67 *
Debra Grochmal

Rubin Gruber....................... 4,621 * 4,069 552 *

Richard Hannapel................... 167(15) * 58 109 *

Marcia Haskell..................... 1,126(16) * 200 926 *

Allen Hauf (17).................... 8,998(18) * 5,510 3,488 *

John Helle......................... 76 * 76 0 *

Donald Jette....................... 278 * 278 0 *

Robert Jungkman.................... 166 * 166 0 *

Gilbert Kaufman (19)............... 5,922(20) * 2,665 3,257 *

Joseph Keelan...................... 66 * 59 7 *

Dennis Kirshy...................... 6,820 * 6,138 682 *

Allan Kline........................ 3,274 * 2,947 327 *

Peter Livingstone.................. 389 * 350 39 *

Lance Lee.......................... 189 * 189 0 *

Edward Los......................... 1,502(21) * 411 1,091 *

Warren Maxwell..................... 250 * 225 25 *

Dennis McCracken................... 2,070 * 2,070 0 *

Leigh Michl........................ 181,217(22) * 308 180,909 *

Steve Mulawski..................... 3,786(23) * 1,561 2,225 *

Thomas Mullaney.................... 482 * 434 48 *

Harry Newton....................... 8,974 * 4,477 4,497 *

Rodger Nordblom.................... 15,286 * 13,757 1,529 *

Naresh Parmar...................... 1,023(24) * 477 546 *

Louis Piazza....................... 997 * 897 100 *

Ronald Pullis...................... 445 * 400 45 *

Joseph Reilly...................... 129 * 116 13 *

Peter Rood (25).................... 4,954(26) * 808 4,146 *

Mitchell Sayare.................... 5,079(27) * 4,571 508 *
Susan Whitehead

James Schwalbe..................... 4,824(28) * 2,381 2,443 *

Reid Simpson....................... 1,720(29) * 367 1,353 *

Kevin Smith (30)................... 5,426(31) * 4,883 543 *
Kathryn Smith

Kenneth Stess (32)................. 8,525(33) * 308 8,217 *

Cassie Dalton Stess Trust (34)..... 445 * 400 45 *

Brian Swoger....................... 467 * 467 0 *

Kim Ward........................... 376(35) * 25 351 *

Michael Wood....................... 1,235(36) * 481 754 *

Terry Young........................ 289 * 260 29 *

Charles River Partnership VII 180,875 * 162,787 18,088 *
(37).............................

HarvourVest Partners V--Direct Fund 216,630 * 194,967 21,663 *
L.P..............................

Interstock Anstalt................. 3,425 * 3,082 343 *

Le Serre (38,39)................... 184,492 * 3,255 181,237 *

PCC Transfer Limited Partnership 72,350 * 65,115 7,235 *
(40).............................

Pioneer Ventures Limited 108,525 * 97,672 10,853 *
Partnership II (41)..............

SVE Star Ventures Enterprises No. 83,872 * 75,485 8,387 *
V................................

SVM Star Ventures Management GmbH 18,896 * 17,006 1,890 *
Nr. 3 & Co. Beteiligungs KG......

The MHF Sylvan Fund................ 16,374 * 14,737 1,637 *

Waterline Capital, LLC............. 22,609 * 20,348 2,261 *

TOTAL.............................. 1,062,713(42) 2.9% 924,458 138,255(43) *

- ------------------------

* Less than 1%

(A) Beneficial ownership is determined in accordance with the rules of the
Securities and Exchange Commission (the "Commission"). Beneficial ownership
includes options to purchase common stock exercisable as of July 9, 1999 and
options to purchase common stock that will become exercisable within 60 days
of July 9, 1999 ("presently exercisable stock options"). Presently
exercisable stock

options are deemed outstanding for purposes of computing the percentage
ownership of the person holding such options, but are not deemed outstanding
for computing the percentage of any other person.

1 Philip Arrigo and Frances Arrigo share voting and investment power with
respect to all of such shares.

2 Includes 146 shares of common stock issuable pursuant to presently
exercisable stock options.

3 Former Vice President of Finance and Administration for RAScom, Inc.

4 Mr. Basile has sole voting and investment power with respect to 1,104 of
such shares and shared voting and investment power with respect to 2,380 of
such shares.

5 Margo Bik and Nicholas Bik share voting and investment power with respect to
all of such shares.

6 Mr. Dick has sole voting and investment power with respect to 1,808 of such
shares and has shared voting and investment power with respect to 180,875 of
such shares. Mr. Dick disclaims beneficial ownership of 180,875 of such
shares. Mr. Dick is a Manager of PCC Transfer GP, LLC, the general partner
of PCC Transfer Limited Partnership. PCC Transfer Limited Partnership is the
owner of 72,350 shares of common stock. Mr. Dick is also Vice President of
Pioneer Management SBIC Corp., the general partner of Pioneer Ventures
Management, L.P. which is the general partner of Pioneer Ventures Limited
Partnership II. Pioneer Ventures Limited Partnership II is the owner of
108,525 shares of common stock.

7 Aaron and Frayda Galvin are the parents of Mark Galvin, former President and
CEO of RAScom and currently a Vice President of Excel.

8 Aaron Galvin and Frayda Galvin share voting and investment power with
respect to 16,059 of such shares and Frayda Galvin has sole voting power
with respect to 400 of such shares.

9 Former President and CEO of RAScom. Currently a Vice President of Excel.

10 Includes 2,399 shares of common stock issuable pursuant to presently
exercisable stock options.

11 Worked as a contract engineer with both Excel and RAScom prior to the
Merger.

12 Mr. Gieseler is the General Manager of RAScom GmbH, a wholly owned
subsidiary of RAScom, Inc.

13 Includes 1,864 shares of common stock issuable pursuant to previously
exercisable stock options.

14 Robert Grochmal and Debra Grochmal share voting and investment power with
respect to all of such shares.

15 Includes 103 shares issuable pursuant to presently exercisable stock
options.

16 Includes 904 shares issuable pursuant to presently exercisable stock
options.

17 Former Vice President and Director of Marketing for RAScom.

18 Includes 2,876 shares issuable pursuant to presently exercisable stock
options.

19 Vice President of Engineering for RAScom

20 Includes 2,961 shares issuable pursuant to presently exercisable stock
options.

21 Includes 1,058 shares issuable pursuant to presently exercisable stock
options.

22 Leigh Michl has sole voting and investment power with respect to 342 of such
shares and has shared voting and investment power with respect to 180,875 of
such shares. Leigh Michl disclaims beneficial ownership of 180,875 of such
shares. Leigh Michl is a Manager of PCC Transfer GP, LLC, the general
partner of PCC Transfer Limited Partnership. PCC Transfer Limited
Partnership is the owner of 72,350 shares of common stock. Leigh Michl is
also Vice President of Pioneer Management SBIC

Corp., the general partner of Pioneer Ventures Management, L.P. which is the
general partner of Pioneer Ventures Limited Partnership II. Pioneer Ventures
Limited Partnership II is the owner of 108,525 shares of common stock.

23 Includes 2,051 shares issuable pursuant to presently exercisable stock
options.

24 Includes 493 shares issuable pursuant to presently exercisable stock
options.

25 Former Vice President of Operations for RAScom.

26 Includes 4,056 shares issuable pursuant to presently exercisable stock
options.

27 Mr. Sayare and Ms. Whitehead share voting and investment power with respect
to all of such shares.

28 Includes 2,178 shares issuable pursuant to presently exercisable stock
options. Of the 2,646 shares already issued, Mr. Schwalbe has sole voting
power with respect to all of such shares, has sole investment power with
respect to 1,780 of such shares and has shared investment power with respect
to 866 of such shares.

29 Includes 1,312 shares issuable pursuant to presently exercisable stock
options.

30 Mr. Smith is the brother-in-law of Mr. Galvin, the former President and CEO
of RAScom and currently a Vice President of Excel.

31 Mr. Smith and Ms. Smith share voting and investment power with respect to
all of such shares.

32 Vice President of Sales for RAScom.

33 Includes 8,183 shares issuable pursuant to presently exercisable stock
options.

34 Mr. Kenneth Stess is the trustee of the Cassie Dalton Stess Trust.

35 Includes 348 shares issuable pursuant to presently exercisable stock
options.

36 Includes 701 shares issuable pursuant to presently exercisable stock
options.

37 Mr. Michael Zak, a general partner of the entity that is the general partner
of Charles River Partnership VII was a member of the board of directors of
RAScom from March 1996 until May 10, 1999.

38 Le Serre has sole voting and investment power with respect to 3,617 of such
shares and has shared voting and investment power with respect to 180,875 of
such shares. Le Serre disclaims beneficial ownership of 180,875 of such
shares. Mr. Frank Polestra is the general partner of Le Serre. Mr. Polestra
is a Manager of PCC Transfer GP, LLC, the general partner of PCC Transfer
Limited Partnership. PCC Transfer Limited Partnership is the owner of 72,350
shares of common stock. Mr. Polestra is also President of Pioneer Management
SBIC Corp., the general partner of Pioneer Ventures Management, L.P. which
is the general partner of Pioneer Ventures Limited Partnership II. Pioneer
Ventures Limited Partnership II is the owner of 108,525 shares of common
stock.

39 Mr. Polestra, a general partner of Le Serre was a member of the board of
directors of RAScom until May 10, 1999.

40 Mr. Polestra, a Manager of PCC Transfer GP, LLC, the general partner of PCC
Transfer Limited Partnership was a member of the board of directors of
RAScom until May 10, 1999.

41 Mr. Polestra, President of Pioneer Management SBIC Corp., the general
partner of Pioneer Ventures Management, L.P. which is the general partner of
Pioneer Ventures Limited Partnership II was a member of the board of
directors of RAScom until May 10, 1999.

42 Includes 31,633 shares issuable pursuant to presently exercisable stock
options and disclaims beneficial ownership where applicable.

43 Includes 31,633 shares issuable pursuant to presently exercisable stock
options and disclaims beneficial ownership where applicable.

PLAN OF DISTRIBUTION

The shares of common stock of Excel offered under this prospectus may be
sold from time to time by or for the account of any of the selling
securityholders or by those individuals and entities to whom they pledge,
donate, distribute or transfer their shares or other successors in interest.

The selling securityholders received the shares of common stock offered
under this prospectus from Excel in connection with our acquisition of RAScom
completed on May 10, 1999. In connection with that acquisition, RAScom retained
NationsBanc Montgomery Securities LLC as its investment banker. Excel paid
$750,000 to NationsBanc Montgomery Securities LLC for services rendered to
RAScom in connection with the acquisition.

Excel will not receive any of the proceeds from the sale of these shares by
the selling securityholders. Excel is paying the expenses of registering these
shares for offer and sale by the selling stockholders. Such expenses include,
but are not limited to, legal fees, accounting fees, various filing fees and
other expenses incident to registering these shares. Excel is not paying any
expenses incurred by the selling stockholders. Such expenses may include, but
are not limited to, underwriting or brokerage commissions and the fees and
expenses of their counsel or other advisers. Excel has agreed to indemnify the
selling stockholders against certain liabilities, including liabilities under
the Securities Act of 1933, and the Securities Exchange Act of 1934 arising in
connection with this prospectus.

The distribution of the shares of common stock of Excel offered under this
prospectus by the selling securityholders is not subject to any underwriting
agreement. The shares may be sold under this prospectus directly to purchasers
by the selling securityholders in negotiated transactions; by or through brokers
or dealers in ordinary brokerage transactions or transactions in which the
broker solicits purchasers; block trades in which the broker or dealer will
attempt to sell the shares as agent but may position and resell a portion of the
block as principal; transactions in which a broker or dealer purchases as
principal for resale for its own account; or through underwriters or agents. The
shares of common stock of Excel offered under this prospectus may be sold at a
fixed offering price, which may be changed, at the prevailing market price at
the time of sale, at prices related to such prevailing market price or at
negotiated prices. Any brokers, dealers, underwriters or agents may arrange for
others to participate in any such transaction and may receive compensation in
the form of discounts, commissions or concessions from the selling
securityholders and/or the purchasers of the shares. Each selling stockholder
will be responsible for payment of any and all commissions to brokers.

The selling securityholder may also loan or pledge the shares registered
under this prospectus to a broker-dealer and the broker-dealer may sell the
shares so loaned or upon a default the broker-dealer may effect sales of the
pledged shares using this prospectus.

If and when any of the shares covered by this prospectus qualifies for sale
under Rule 144 under the Securities Act, they may be sold under Rule 144 rather
than under this prospectus.

Any selling securityholder and any broker-dealer, agent or underwriter that
participates with the selling securityholder in the distribution of the shares
of common stock of Excel offered under this prospectus may be deemed to be
"underwriters" within the meaning of the Securities Act, in which event any
commissions received by such broker-dealers, agents or underwriters and any
profit on the resale of the shares purchased by them may be deemed to be
underwriting commissions or discounts under the Securities Act.

The selling securityholders are not restricted as to the price or prices at
which they may sell the shares of common stock of Excel offered under this
prospectus. Sales of such shares at less than the market price may depress the
market price of Excel's securities. Moreover, the selling securityholders are
not restricted as to the number of shares which may be sold at any one time, and
it is possible that a significant number of shares could be sold at the same
time which may also depress the market price of Excel's securities.

Under applicable rules and regulations under the Exchange Act, any person
engaged in the distribution of the shares of common stock of Excel offered under
this prospectus may not simultaneously engage in market making activities with
respect to the shares for a period of time prior to the commencement of such
distribution. In addition, each selling securityholder will be subject to
applicable provisions of the Exchange Act and the rules and regulations under
the Exchange Act, including, but not limited to, Rule 10b-5 and Regulation M,
which provisions may limit the timing of purchases and sales of the shares by
the selling securityholder.

There is no assurance that any selling securityholder will sell any or all
of the shares described in this prospectus and may transfer, devise or gift such
securities by other means not described in this prospectus.

Expenses of preparing and filing the registration statement and all
post-effective amendments will be borne by Excel.

Excel is permitted to suspend the use of this prospectus in connection with
sales of the shares of common stock of Excel offered under this prospectus by
holders during periods of time if there then exists material, non-public
information relating to Excel which, in the reasonable opinion of Excel, would
not be appropriate for disclosure at that time.

Excel will use all commercially reasonable efforts to cause this prospectus
to remain effective until May 10, 2000 unless earlier terminated as a result of
the acquisition of Excel by Lucent.

LEGAL MATTERS

The validity of the shares of common stock of Excel offered hereby will be
passed upon by Testa, Hurwitz & Thibeault, LLP, Boston, Massachusetts.

EXPERTS

The consolidated financial statements of Excel incorporated by reference in
this prospectus and elsewhere in the registration statement have been audited by
Arthur Andersen LLP, independent public accountants, as indicated in their
reports with respect thereto, and are incorporated herein in reliance upon the
authority of said firm as experts in auditing and accounting.

WHERE YOU CAN FIND MORE INFORMATION

Excel files annual, quarterly and special reports, proxy statements and
other information with the SEC. You may read and copy any document we file with
the SEC at the SEC's Public Reference Room at 450 Fifth Street, N.W.,
Washington, D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further
information on operation of the Public Reference Room. Our SEC filings are also
available to the public from the SEC's website at "http://www.sec.gov." Our
website is located at "http://www.xl.com." Information contained on our website
is not part of this prospectus.

The SEC allows Excel to "incorporate by reference" the information we file
with them, which means that we can disclose important information to you by
referring you to other documents previously filed with the SEC, including
Excel's annual, current and quarterly reports. The information incorporated
herein by reference is considered to be part of this document, except to the
extent such information is modified or superseded by information provided
herein. Any information that we file later with the SEC, specifically those
documents filed pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange
Act will automatically update and supersede the information in this Prospectus:

The following documents have been filed by Excel with the SEC (File No.
0-23263):

1. Annual report on Form 10-K for the year ended December 31, 1998;

2. Excel's proxy statement, filed on April 9, 1999, for the annual meeting
of shareholders for the fiscal year ended December 31, 1998;

3. Quarterly reports on Form 10-Q for the quarters ended March 31, 1999 and
June 30, 1999, filed with the Commission on May 18, 1999 and August 16,
1999 respectively;

4. Excel's Current Report on Form 8-K, dated April 15, 1999 and filed April
23, 1999 announcing the signing of the RAScom acquisition.

5. Excel's Current Report on Form 8-K dated May 10, 1999 and filed May 25,
1999, announcing the completion of the RAScom acquisition; as amended by
Amendment No. 1 filed July 23, 1999 providing pooled financial statements
of RAScom and Excel as if the two entities had operated as one since
inception; as further amended by Amendment No.2 filed July 29, 1999
providing additional financial information; and all as further amended by
Amendment No.3 filed August 27, 1999 updating certain of the financial
statements provided in Amendment No.1.

6. Excel's Current Report on Form 8-K, dated August 17, 1999 and filed
August 26, 1999 announcing the acquisition of Excel by Lucent
Technologies, Inc.

7. The "Description of Registrant's Securities to be Registered" contained
in Excel's registration statement filed on Form 8-A, filed on October 23,
1997.

You may request a copy of all of the information incorporated by reference
herein, at no cost, by writing or telephoning our Chief Financial Officer at the
following address:

Excel Switching Corporation
255 Independence Drive
Hyannis, MA 02601
(508) 862-3000

This prospectus is part of a registration statement we filed with the SEC.
You should rely only on the information or representations provided in this
prospectus. We have authorized no one to provide you with different information.
We are not making an offer of these securities in any state where the offer is
not permitted. You should not assume that the information in this prospectus is
accurate as of any date other than the date on the front of the document.

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

ITEM 14. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION.

The following table sets forth an estimate (other than with respect to the
Registration Fee and the Nasdaq National Market additional listing fee expense)
of the expenses expected to be incurred in connection with the issuance and
distribution of the securities being registered, other than underwriting
discounts and commissions:

Registration Fee--Securities and Exchange Commission............ $9,227.88
Nasdaq National Market Additional Listing Fee................... $17,500.00
Accounting Fees and Expenses.................................... $5,000.00
Legal Fees and Expenses......................................... $40,000.00
Miscellaneous................................................. $5,000.00
---------
---------
TOTAL......................................................... $76,727.88

Excel will bear all expenses shown above.

ITEM 15. INDEMNIFICATION OF DIRECTORS AND OFFICERS.

Excel is required by its Restated By-laws and its Restated Articles of
Organization to generally indemnify any director, officer or employee against
all expenses and liabilities reasonably incurred by or imposed upon such person
in connection with any legal action in which such person is involved by reason
of such person's position with Excel unless such person shall have been finally
adjudicated in any action, suit or proceeding not to have acted in good faith in
the reasonable belief that such person's action was in the best interests of
Excel. Excel may pay expenses incurred by any such person in defending a civil
or criminal action or proceeding in advance of the final disposition of such
action upon Excel's receipt of the undertaking of such person to repay such
amount if such person shall be adjudicated not to be entitled to
indemnification.

Excel's Restated Articles of Organization include a provision limiting the
personal liability of a director of Excel to its stockholders for monetary
damages for breaches of their fiduciary duty except (i) for any breach of the
director's duty of loyalty to Excel or its stockholders, (ii) for acts or
omissions not in good faith or which involve intentional misconduct or a knowing
violation of law, (iii) under section sixty-one or sixty-two of Chapter 156B of
the Massachusetts General Laws, or (iv) for any transaction from which the
director derived an improper benefit.

Excel maintains directors and officers liability insurance for the benefit
of its directors and certain of its officers.

II-1

ITEM 16. EXHIBITS.

The following exhibits, required by Item 601 of Regulation S-K, are filed as
a part of this Registration Statement. Exhibit numbers, where applicable, in the
left column correspond to those of Item 601 of Regulation S-K.

EXHIBIT NO. ITEM AND REFERENCE
- ------------- -----------------------------------------------------------------------------------------------------

2.1 Agreement and Plan of Merger and Reorganization dated as of April 15, 1999, by and among Excel
Switching Corporation, Racepoint Acquisition Corp., RAScom, Inc., the shareholders of RAScom, Inc.
and Mark B. Galvin as Indemnification Representative (filed as Exhibit 2.1 to the original Report on
Form 8-K, as amended, dated May 10, 1999 and filed with the Commission on May 25, 1999 and hereby
incorporated by reference).

2.2 Amendment No. 1 to the Agreement and Plan of Merger and Reorganization dated as of May 7, 1999, by
and among Excel Switching Corporation, Racepoint Acquisition Corp., RAScom, Inc., those shareholders
of RAScom, Inc. that are signatories thereto, and Mark B. Galvin as Indemnification Representative
(filed as Exhibit 2.2 to the original Report on Form 8-K, as amended, dated May 10, 1999 and filed
with the Commission on May 25, 1999 and hereby incorporated by reference).

4.1 Escrow Agreement dated as of May 10, 1999, by and among Excel Switching Corporation, Racepoint
Acquisition Corp., RAScom, Inc., State Street Bank and Trust Company, the shareholders of RAScom,
Inc. and Mark B. Galvin as Indemnification Representative (filed as Exhibit 4.1 to the original
Report on Form 8-K dated May 10, 1999 and filed with the Commission on May 25, 1999 and hereby
incorporated by reference).

4.2 Side Letter Agreement dated as of May 10, 1999 by and among Excel Switching Corporation, Racepoint
Acquisition Corp., RAScom, Inc., State Street Bank and Trust Company and Mark B. Galvin as
Indemnification Representative (filed as Exhibit 4.2 to the original Report on Form 8-K dated May 10,
1999 and filed with the Commission on May 25, 1999 and hereby incorporated by reference).

4.3 Registration Rights Agreement, dated as of May 10, 1999, between the shareholders of RAScom that are
signatories thereto and Excel Switching Corporation (filed as Exhibit 4.3 to the original Report on
Form 8-K dated May 10, 1999 and filed with the Commission on May 25, 1999 and hereby incorporated by
reference).

5.1 Legal Opinion of Testa, Hurwitz & Thibeault, LLP (filed herewith)

23.1 Consent of Arthur Andersen LLP (filed herewith)

23.2 Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1)

24 Power of Attorney (contained on Signature Pages)

ITEM 17. UNDERTAKINGS.

(a) The undersigned registrant hereby undertakes:

(1) To file, during any period in which offers or sales are being made, a
post-effective amendment to this registration statement:

(i) To include any prospectus required by Section 10(a)(3) of the
Securities Act of 1933;

(ii) To reflect in the prospectus any facts or events arising after the
effective date of the registration statement (or the most recent
post-effective amendment thereof) which, individually or in

II-2

the aggregate, represents a fundamental change in the information set forth
in the registration statement. Notwithstanding the foregoing, any increase
or decrease in volume of securities offered (if the total dollar value of
securities offered would not exceed that which was registered) and any
deviation from the low or high end of the estimated maximum offering range
may be reflected in the form of prospectus filed with the Commission
pursuant to Rule 424(b) if, in the aggregate, the changes in volume and
price represent no more than 20 percent change in the maximum aggregate
offering price set forth in the "Calculation of Registration Fee" table in
the effective registration statement.

(iii) To include any material information with respect to the plan of
distribution not previously disclosed in the registration statement or any
material change to such information in the registration statement.

(2) That, for the purpose of determining any liability under the Securities
Act of 1933, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial BONA
FIDE offering thereof.

(3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of the
offering.

(b) The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act of 1934 (and, where applicable, each filing of an employee benefit
plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of
1934) that is incorporated by reference in the registration statement shall be
deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial BONA FIDE offering thereof.

(c) Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
registrant pursuant to provisions described in Item 14 above, or otherwise, the
registrant has been advised that in the opinion of the Securities and Exchange
Commission such indemnification is against public policy as expressed in the
Securities Act of 1933 and is, therefore, unenforceable. In the event that a
claim for indemnification against such liabilities (other than the payment by
the registrant of expenses incurred or paid by a director, officer or
controlling person of the registrant in the successful defense of any action,
suit or proceeding) is asserted by such director, officer or controlling person
in connection with the securities being registered, the registrant will, unless
in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the
Securities Act of 1933 and will be governed by the final adjudication of such
issue.

II-3

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-3 and has duly caused this Registration
Statement on Form S-3 to be signed on its behalf by the undersigned, thereunto
duly authorized in the Town of Hyannis, Commonwealth of Massachusetts on August
27, 1999.

EXCEL SWITCHING CORPORATION

By: /s/ ROBERT MADONNA
-----------------------------------------
Robert Madonna
PRESIDENT AND CHIEF EXECUTIVE OFFICER

POWER OF ATTORNEY

We, the undersigned officers and directors of Excel Switching Corporation,
hereby severally constitute and appoint Christopher Stavros and Stephen S.
Galliker, and each of them singly, our true and lawful attorneys, with full
power to them and each of them singly, to sign for us in our names in the
capacities indicated below, any amendments to this Registration Statement on
Form S-3 (including post-effective amendments), and to file the same, with all
exhibits thereto and other documents in connection therewith, with the
Securities and Exchange Commission, and generally to do all things in our names
and on our behalf in our capacities as officers and directors of Excel Switching
Corporation to enable Excel Switching Corporation to comply with the provisions
of the Securities Act of 1933, as amended, hereby ratifying and confirming our
signatures as they may be signed by our said attorneys, or any of them, to said
Registration Statement and all amendments thereto.

Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons on behalf
of the Registrant and in the capacities and on the dates indicated.

NAME CAPACITY DATE
- ------------------------------ --------------------------- -------------------
Director, President and
/s/ ROBERT MADONNA Chief Executive Officer
- ------------------------------ (Principal Executive August 27, 1999
Robert Madonna Officer)
Vice President, Finance and
/s/ STEPHEN S. GALLIKER Administration and Chief
- ------------------------------ Financial Officer August 27, 1999
Stephen S. Galliker (Principal Financial and
Accounting Officer)
/s/ CHRISTOPHER STAVROS Director, Vice President,
- ------------------------------ General Counsel and Clerk August 27, 1999
Christopher Stavros

/s/ EDWARD L. BRESLOW Director
- ------------------------------ August 27, 1999
Edward L. Breslow

/s/ JOHN LOUGHLIN Director
- ------------------------------ August 27, 1999
John Loughlin

II-4

INDEX TO EXHIBITS

EXHIBIT NO. ITEM AND REFERENCE
- ------------- -----------------------------------------------------------------------------------------------------

5.1 Legal Opinion of Testa, Hurwitz & Thibeault, LLP (filed herewith)

23.1 Consent of Arthur Andersen LLP (filed herewith)

23.2 Consent of Testa, Hurwitz & Thibeault, LLP (included in Exhibit 5.1)

24 Power of Attorney (contained on Signature Page)