1
                                  EXHIBIT 10.2


                          APPLIED DIGITAL ACCESS, INC.

                       1997 REGISTRATION RIGHTS AGREEMENT

         This 1997 Registration Rights Agreement (this "Agreement") made as of
June 27, 1997 by and between Applied Digital Access, Inc., a California
corporation (the "Company") and Northern Telecom Limited, a Canadian corporation
("Nortel").

         WHEREAS, the Company and Nortel have entered into that certain Stock
and Warrant Purchase Agreement dated the date hereof (the "Stock and Warrant
Purchase Agreement"), pursuant to which the Company has agreed to issue to
Nortel, and Nortel has agreed to receive a warrant to purchase 150,000 shares of
the Company's Common Stock (the "Warrant") and, in certain circumstances, shares
of the Company's Common Stock (collectively, the "Shares").

         In consideration of the mutual agreements, covenants and conditions
contained herein, the Company and Nortel hereby agree as follows:

                                    SECTION 1

                               REGISTRATION RIGHTS

         The Company hereby grants to Nortel the registration rights set forth
in this Section 1, with respect to the Registrable Securities (as hereinafter
defined) owned by Nortel. The Company and Nortel agree that the registration
rights provided herein set forth the sole and entire agreement on the subject
matter between the Company and Nortel.

         1.1 Definitions. As used in this Section 1:

             (a) The term "NASD" means the National Association of Securities
Dealers, Inc.

             (b) The term "NASDAQ" means the National Association of Securities
Dealers, Inc. Automated Quotation System.

             (c) The terms "register," "registered," and "registration" refer to
a registration effected by filing with the Securities and Exchange Commission
(the "SEC") a registration statement (the "Registration Statement") in
compliance with the Securities Act of 1933, as amended (the "1933 Act") and the
declaration or ordering by the SEC of the effectiveness of such Registration
Statement.

             (d) The term "Registrable Securities" means (i) the Shares issued
to Nortel pursuant to the Stock and Warrant Purchase Agreement, if any, (ii)
shares of Common Stock of the Company issued to Nortel upon exercise of the
Warrant (the "Warrant Shares") and (iii) any Common Stock of the Company issued
as (or issuable



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upon the conversion or exercise of any warrant, right, or other security that is
issued as) a dividend or other distribution with respect to, or in exchange or
in replacement of the Common Stock or the Warrant Shares described in (i) and/or
(ii) of this Section 1.1 (d). In the event of any recapitalization by the
Company from the date hereof going forward, whether by stock split, reverse
stock split, stock dividend or the like, the number of shares of Registrable
Securities used throughout this Agreement for various purposes shall be
proportionately increased or decreased.

         (e) The term "Registration Expenses" means all expenses incident to the
Company's performance of or compliance with Section 1, including without
limitation all registration, filing and applicable fees of the SEC, stock
exchange or NASD registration or filing fees and all listing fees and fees with
respect to the inclusion of securities in NASDAQ, all fees and expenses of
complying with state securities or blue sky laws (including fees and
disbursements of counsel to the underwriters or Nortel in connection with "blue
sky" qualification of the Registrable Securities and determination of their
eligibility for investment under the laws of various jurisdictions), all
duplicating and printing expenses, all messenger and delivery expenses, the fees
and disbursements of counsel for the Company and of its independent public
accountants including the expenses of "cold comfort" letters required by or
incident to such registration, all fees and disbursements of underwriters
customarily paid by issuers or sellers of securities and all transfer taxes;
provided, however, that Registration Expenses shall exclude underwriters' fees
and underwriting discounts and commissions in respect of the Registrable
Securities being registered and the fees and expenses of counsel to Nortel.

         1.2 Company Registration.

             (a) If at any time or from time to time the Company shall determine
to register any of its securities, either for its own account or the account of
security holders (other than Nortel), other than a registration relating solely
to employee benefit plans, or a registration on Form S-4 relating solely to an
SEC Rule 145 transaction, the Company shall:

                 (i) promptly give Nortel written notice thereof (which shall be
given at least 30 days prior to filing and shall include a list of the
jurisdictions in which the Company intends to attempt to qualify such securities
under the applicable blue sky or other state securities laws); and

                 (ii) include in such registration (and any related
qualification under blue sky laws or other compliance), and in any underwriting
involved therein, all the Registrable Securities specified in a written request
or requests, made within twenty (20) days after receipt of such written notice
from the Company, by Nortel, except as set forth in Section 1.2(b) below.

             (b) If the registration of which the Company gives notice is for a
registered public offering involving an underwriting, the Company shall so
advise Nortel as a part of the written notice given pursuant to Section
1.2(a)(i). In such event the right



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of Nortel to require registration pursuant to this Section 1.2 shall be
conditioned upon Nortel's participation in such underwriting and the inclusion
of Nortel's Registrable Securities in the underwriting to the extent provided
herein. If Nortel proposes to distribute its securities through such
underwriting, Nortel, together with the Company and the other parties
distributing their securities through such underwriting, shall enter into an
underwriting agreement in customary form with the underwriter or underwriters
selected for such underwriting by the Company. Nortel may, at its option,
require that any or all of the representations and warranties by, and the other
agreements on the part of, the Company to and for the benefit of such
underwriters shall also be made to and for the benefit of Nortel and that any or
all of the conditions precedent to the obligations of such underwriters under
such underwriting agreement shall also be conditions precedent to the
obligations of Nortel. Nortel shall not be required to make any representations
or warranties to or agreements with the Company or the underwriters other than
representations, warranties or agreements regarding Nortel, Nortel's ownership
of and title to the Registrable Securities, Nortel's intended method of
distribution and any other representations required by law or regulation, and
the liability of Nortel to any underwriter or other person under such
underwriting agreement shall be limited to liability arising from misstatements
in or omissions from its representations and warranties and shall be limited to
the amount of the net proceeds received by Nortel in the offering; provided,
however, that the provisions of any underwriting agreement executed by the
Company and Nortel will supersede any conflicting provisions of this Agreement.
Notwithstanding any other provision of this Section 1.2, if the underwriter
determines that marketing factors require a limitation of the number of shares
to be underwritten, the underwriter may limit the number of Registrable
Securities to be included in the registration and underwriting, or may exclude
Registrable Securities entirely from such registration and underwriting subject
to the terms of this Section. The Company shall so advise Nortel of the
Company's securities that would otherwise be registered and underwritten
pursuant hereto, and the number of shares of such securities, including
Registrable Securities, that may be included in the registration and
underwriting shall be allocated in the following manner: (i) shares proposed by
the Company to be sold for its own account shall be included first, and (ii) any
Registrable Securities requested to be included in such registration and any
other shares proposed to be included by any other Person holding securities of
the Company that has been granted registration rights shall thereafter be
included, pro rata among the holders thereof requesting such registration on the
basis of the number of shares of such securities requested to be included by
such holders. If Nortel disapproves of the terms of the underwriting, it may
elect to withdraw therefrom by written notice to the Company and the
underwriter. The Registrable Securities so withdrawn shall also be withdrawn
from registration.

             (c) There is no limitation on the number of registrations which the
Company may effect pursuant to this Section 1.2. The Company will pay all
Registration Expenses in connection with any registration of Registrable
Securities pursuant to this Section 1.2.



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         1.3 Obligations of the Company. Whenever required under this Section 1
to effect the registration of any Registrable Securities, the Company shall, as
expeditiously as reasonably possible:

             (a) Prepare and file with the SEC a registration statement with
respect to such Registrable Securities as expeditiously as possible (and in any
event within 120 days after the relevant request for registration) and use its
diligent best efforts to cause such registration statement to become effective,
and, upon the request of Nortel, keep such registration statement effective for
up to the earlier of (I) ninety (90) days or (II) until Nortel has completed the
distribution relating thereto.

             (b) Notify Nortel of the SEC's requests for amending or
supplementing the registration statement and the prospectus and prepare and file
with the SEC such amendments and supplements to such registration statement and
the prospectus used in connection with such registration statement as may be
necessary to comply with the provisions of the 1933 Act with respect to the
disposition of all securities covered by such registration statement.

             (c) Furnish to Nortel such numbers of copies of a prospectus,
including a preliminary prospectus, in conformity with the requirements of the
1933 Act, and such other documents as they may reasonably request in order to
facilitate the disposition of Registrable Securities owned by them.

             (d) Use its best efforts to register and qualify the securities
covered by such registration statement under such other securities or Blue Sky
laws of such jurisdictions in the United States as shall be reasonably requested
by Nortel, provided that the Company shall not be required in connection
therewith or as a condition thereto to qualify to do business or to file a
general consent to service of process in any such states or jurisdictions.

             (e) In the event of any underwritten public offering, enter into
and perform its obligations under an underwriting agreement, in usual and
customary form, with the managing underwriter of such offering.

             (f) Notify Nortel at any time when a prospectus relating thereto is
required to be delivered under the 1933 Act of the happening of any event as a
result of which the prospectus included in such registration statement, as then
in effect, includes an untrue statement of a material fact or omits to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in the light of the circumstances then existing.

             (g) Before filing any registration statement or any amendment or
supplement thereto (or any comparable statements under securities or blue sky
laws of any jurisdiction containing any different disclosure), furnish
substantially final copies of such documents to Nortel.



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             (h) Use its best efforts to cause all Registrable Securities
covered by such registration statement to be listed on a national securities
exchange or to secure designation of all such Registrable Securities as a NASDAQ
"national market system security" within the meaning of Rule 11Aa2-1 under the
1934 Act (as defined below), in each case to the extent the shares of the
Company's common stock are so listed or designated.

             (i) Make available its officers and personnel to the underwriters,
if any, and otherwise provide reasonable assistance to the underwriters, if any,
in their marketing of Registrable Securities.

         1.4 Indemnification.

             (a) The Company shall, and does hereby undertake to, indemnify and
hold harmless Nortel, each of Nortel's officers and directors and each person
controlling Nortel, with respect to any registration, qualification or
compliance effected pursuant to this Section 1 of the Registrable Securities
held by or issuable to Nortel, and each underwriter of the Registrable
Securities, if any, and each person who controls Nortel or any underwriter,
against all claims, losses, damages and liabilities (or actions or proceedings
in respect thereto whether commenced or threatened) to which they may become
subject under the 1933 Act, the Securities Exchange Act of 1934, as amended,
(the "1934 Act"), or other federal or state law arising out of or based on (i)
any untrue statement (or alleged untrue statement) of a material fact contained
in any prospectus, offering circular or other similar document (including any
related Registration Statement, notification, preliminary prospectus, amendment
or supplement thereto, documents incorporated by reference therein or the like)
incident to any such registration, qualification or compliance, or based on any
omission (or alleged omission) to state therein a material fact required to be
stated therein or necessary to make the statements therein not misleading, or
(ii) any violation or alleged violation by the Company of any federal, state or
common law rule or regulation applicable to the Company in connection with any
such registration, qualification or compliance, and shall reimburse, as
incurred, Nortel, each such underwriter, and each such director, officer agent
and controlling person, for any legal and any other expenses reasonably incurred
in connection with investigating or defending any such claim, loss, damage,
liability, action or proceeding; provided that the Company shall not be liable
in any such case hereunder to the extent that any such claim, loss, damage,
liability, or expense arises out of or is based on any untrue statement or
omission in reliance upon and in conformity with written information furnished
to the Company by an instrument duly executed by Nortel or such underwriter, as
the case may be.

             (b) Nortel, if Registrable Securities held by or issuable to Nortel
are included in such registration, qualification or compliance, shall indemnify
the Company, each of its directors, and each officer who signs a Registration
Statement in connection therewith, and each person controlling the Company, each
underwriter, if any, and each person who controls Nortel or any underwriter,
against all claims, losses, damages and liabilities (or actions or proceedings
in respect thereof whether commenced or



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threatened) arising out of or based on any untrue statement (or alleged untrue
statement) of a material fact contained in any such Registration Statement,
prospectus, offering circular or other document, or any omission (or alleged
omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, and shall reimburse, as
incurred, the Company, each such underwriter and each such director, officer,
partner, and controlling person, for any legal or any other expenses reasonably
incurred in connection with investigating or defending any such claim, loss,
damage, liability, action, or proceeding, in each case to the extent, but only
to the extent, that such untrue statement (or alleged untrue statement) or
omission (or alleged omission) was made in such Registration Statement,
prospectus, offering circular or other document, in reliance upon and in
conformity with written information furnished to the Company by an instrument
duly executed by Nortel. Notwithstanding any other provision of this Agreement,
Nortel's liability hereunder shall be limited to the amount of the net proceeds
received by Nortel in the offering with respect to which indemnity is being
sought.

             (c) Each party entitled to indemnification under this Section 1.4
(the "Indemnified Party") shall give notice to the party required to provide
such indemnification (the "Indemnifying Party") of any claim as to which
indemnification may be sought promptly after such Indemnified Party has actual
knowledge thereof, and shall permit the Indemnifying Party to assume the defense
of any such claim or any litigation resulting therefrom; provided that counsel
for the Indemnifying Party, who shall conduct the defense of such claim or
litigation, shall be subject to approval by the Indemnified Party (whose
approval shall not be reasonably withheld) and the Indemnified Party may
participate in such defense at the Indemnifying Party's expense if
representation of such Indemnified Party would be inappropriate due to actual or
potential differing interests between such Indemnified Party and any other party
represented by such counsel in such proceeding; and provided further that the
failure of any Indemnified Party to give notice as provided herein shall not
relieve the Indemnifying Party of its obligations under this Section 1.4, except
to the extent that such failure to give notice shall materially adversely affect
the Indemnifying Party in the defense of any such claim or any such litigation.
No Indemnifying Party, in the defense of any such claim or litigation, shall
consent, except with the consent of each Indemnified Party, to entry of any
judgment or enter into any settlement that does not include as an unconditional
term thereof the giving by the claimant or plaintiff therein, to such
Indemnified Party, of a release from all liability in respect to such claim or
litigation.

             (d) If the indemnification provided for in this Section 1.4 shall
for any reason be held by a court to be unavailable to an indemnified party
under subsection (a) or (b) hereof in respect of any claim, loss, damage or
liability, or any action or proceeding in respect thereof, then, in lieu of the
amount paid or payable under subsection (a) or (b) hereof, the indemnified party
and the indemnifying party under subsection (a) or (b) shall contribute to the
aggregate, claims, losses, damages and liabilities (including legal or other
expenses reasonably incurred in connection with investigating the same), (i) in
such proportion as is appropriate to reflect the relative fault of the Company
and Nortel which resulted in such claim, loss, damage or liability,



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or action or proceeding in respect thereof, as well as any other relevant
equitable considerations or (ii) if the allocation provided by clause (i) above
is not permitted by applicable law, in such proportion as shall be appropriate
to reflect not only the relative fault but also the relative benefits received
by the Company and Nortel from the offering of the securities covered by such
registration statement as well as relevant equitable considerations. The parties
hereto agree that it would not be just and equitable if contributions pursuant
to this Section 1.4(d) were to be determined by pro rata allocation or by any
other method of allocation which does not take account of the equitable
considerations referred to above. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the 1933 Act) shall be
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation. In addition, no person shall be obligated to contribute
hereunder any amounts in payment for any settlement of any action or claim
effected without such person's consent, which consent shall not be unreasonably
withheld. Notwithstanding anything in this subsection (d) to the contrary, no
indemnifying party (other than the Company) shall be required to contribute any
amount in excess of the net proceeds received by such party from the sale of the
Registrable Securities in the offering to which the claims, losses, damages or
liabilities of the indemnified parties relate.

         1.5 Information by Nortel. Nortel, if included in any registration,
shall furnish to the Company such information regarding Nortel and the
distribution proposed by Nortel as the Company may reasonably request in writing
and as shall be required in connection with any registration, qualification or
compliance referred to in this Section 1.

         1.6 Temporary Cessation of Offers and Sales by Shareholders. Nortel
acknowledges that there may be times when the Company may be required to suspend
the use of the prospectus forming part of the Registration Statement (including
foregoing a request that the Registration Statement become effective) until such
time as an amendment to the Registration Statement has been filed by the Company
and declared effective by the SEC, until the prospectus is supplemented or
amended to comply with the 1933 Act, or until such time as the Company has filed
an appropriate report with the SEC pursuant to the Exchange Act, but only if
pursuant to advice of counsel (i) the filing of a registration statement would
require premature disclosure of information, the disclosure of which could have
an adverse effect on the business or operations of the Company, or would in the
good faith opinion of the Company not be in the Company's best interests at such
time, or (ii) the Company then is unable to comply with the requirements of the
SEC relating to such registration or to resale of the Registrable Securities,
provided, however, that the Company shall use its reasonable best efforts to
make such disclosure, or remedy such noncompliance including removal of any stop
order, as the case may be, at the earliest practical date that the Company
believes to be in the Company's best interests. In the event of any such
suspension, Nortel may elect to withdraw the Registrable Securities from such
registration by written notice to the Company. Nortel hereby agrees that it will
not sell any Registrable Securities pursuant to said prospectus during the
period commencing at the time at which the Company gives Nortel notice of the
suspension of the use of the prospectus and ending at the time



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the Company gives Nortel notice that Nortel may thereafter effect sales pursuant
to said prospectus, as the same may have been supplemented or amended.

         1.7 Transfer of Registration Rights. The rights, contained in Sections
1.2, 1.3, 1.4 and 1.8 hereof, to cause the Company to register the Registrable
Securities, may be assigned or otherwise conveyed in whole (but only with all
related obligations) to a transferee or assignee of Registrable Securities, who
shall be considered "Nortel" for purposes of this Section 1, provided that the
transferee or assignee is a subsidiary, affiliate or shareholder of Nortel, and
the Company is given written notice by Nortel at the time of or within a
reasonable time after said transfer, stating the name and address of said
transferee or assignee and identifying the securities with respect to which such
registration rights are being assigned.

         1.8 Requested Registration. Nortel may, at any time and from time to
time, make a written request that the Company effect a registration (a
"Requested Registration") on Form S-3 (or any successor form, if permitted) and
any related qualification or compliance with respect to all or a part of the
Registrable Securities owned by Nortel, subject to the limitations set forth
below. In such event, the Company shall as soon as practicable, effect such
registration and all such qualifications and compliances as may be so requested
and as would permit or facilitate the sale and distribution of all or such
portion of Nortel's Registrable Securities as are specified in such request,
provided that the Company shall not be obligated to effect any such
registration, qualification or compliance, pursuant to this Section 1.8:

             (a)  if Form S-3 is not available to the Company for such offering
                  by Nortel;

             (b)  if Nortel proposes to sell Registrable Securities at an
                  aggregate price to the public (net of any underwriters'
                  discounts or commissions) of less than $1,000,000 unless such
                  offering shall cover all remaining Registrable Securities;

             (c)  if the Company shall furnish to Nortel a certificate signed by
                  the president of the Company stating that in the good faith
                  judgment of the Board of Directors of the Company, it would be
                  materially detrimental to the Company and its shareholders for
                  such Requested Registration to be effected at such time,
                  (without taking into account the costs to the Company) and
                  containing a statement of the reasons for such postponement
                  and an approximation of the anticipated delay, in which event
                  the Company shall have the right to defer the filing of the
                  statement related to such Requested Registration for a period
                  of not more than one hundred eighty (180) days after receipt
                  of the request of Nortel under this Section 1.8; provided,
                  however, that the Company shall not utilize this right more
                  than once in any twelve



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                  (12) month period and, in the event of any such postponement,
                  Nortel shall have the right to withdraw its registration
                  request;

             (d)  if the Company has, within the twelve (12) month period
                  preceding the date of such request, already effected two
                  Requested Registrations for Nortel pursuant to this Section
                  1.8; or

             (e)  in any particular jurisdiction in which the Company would be
                  required to qualify to do business or to execute a general
                  consent to service of process in effecting such registration,
                  qualification or compliance.

         Subject to the foregoing, the Company shall file a registration
statement covering the Registrable Securities so requested to be registered as
soon as practicable after receipt of Nortel's request. The Company agrees to
include in any such registration statement all information which, in the
reasonable opinion of counsel to Nortel and counsel to the Company, is required
to be included. Whenever the Company shall effect a registration pursuant to
this Section 1.8 in connection with an underwritten offering by Nortel, no
securities other than Registrable Securities shall be included among the
securities covered by such registration unless Nortel consents to such
inclusion, such inclusion is pursuant to and subject to the terms of the
underwriting agreement or arrangements and such inclusion will not have a
material adverse effect on the offering (including, without limitation, on the
pricing of the offering). Registration Expenses shall be shared equally by the
Company and Nortel with respect to the first Requested Registration. All
expenses incurred in connection with any Requested Registration after the first
Requested Registration has been effected shall be borne by Nortel. Nortel shall,
with respect to all Requested Registrations, be responsible for the payment of
any and all underwriters' fees and underwriting discounts and commissions in
respect of the Registrable Securities being registered and the fees and expenses
of counsel to Nortel.

         The Company further agrees that if it shall have previously received a
request for registration under Section 1.8 hereof, and if such previous
registration shall not have been withdrawn or abandoned, the Company shall not
effect any public or private offer, sale or other distribution of its securities
or effect any registration of any of its securities under the 1933 Act (other
than a registration of Form S-8), whether or not for sale for its own account,
until a period of 90 days (or such shorter period as Nortel shall agree) has
elapsed from the effective date of such previous registration.

         1.9 Delay of Registration. Nortel shall have no right to obtain or seek
an injunction restraining or otherwise delaying any such registration as the
result of any controversy that might arise with respect to the interpretation or
implementation of this Section 1.

         1.10 Rule 144 Reporting. With a view to making available to Nortel the
benefits of certain rules and regulations of the SEC which may permit the sale
of the



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Registrable Securities to the public without registration, the Company agrees to
take all actions reasonably necessary to:

              (a) Make and keep public information available, as those terms are
understood and defined in SEC Rule 144 or any similar or analogous rule
promulgated under the 1933 Act, at all times;

              (b) File with the SEC, in a timely manner, all reports and other
documents required of the Company under the 1933 Act and 1934 Act;

              (c) So long as Nortel owns any Registrable Securities, furnish to
Nortel forthwith upon request: a written statement by the Company as to its
compliance with the reporting requirements of said Rule 144 of the 1933 Act, and
of the 1934 Act; a copy of the most recent annual or quarterly report of the
Company; and such other reports and documents as Nortel may reasonably request
in availing itself of any rule or regulation of the SEC allowing it to sell any
such securities without registration.

         1.11 Amendment of Registration Rights. Any provision of this Section 1
may be amended and the observance thereof may be waived (either generally or in
a particular instance and either retroactively or prospectively), only with the
written consent of the Company and Nortel (or their respective successors or
permitted transferees). Any amendment or waiver effected in accordance with this
Section 1 shall be binding upon Nortel, each future holder of Registrable
Securities and the Company.

         1.12 Termination of Registration Rights. Nortel shall not be entitled
to exercise any right provided for in this Section 1 following the earlier of
(a) June 27, 2000 or (b) such time as Nortel is entitled to sell all of the
Registrable Securities held by Nortel (and Nortel has no remaining rights to
acquire Registrable Securities, upon exercise of the Warrant or otherwise),
without any restriction on manner of transaction or any notice requirements,
within a ninety (90)-day period under SEC Rule 144 (or a successor rule).

         1.13 "Market Stand-Off" Agreement. During the period, specified by the
Company and an underwriter of Common Stock or other securities of the Company,
following the effective date of a registration statement of the Company filed
under the 1933 Act, Nortel shall not, to the extent requested by the Company and
such underwriter, directly or indirectly sell, offer to sell, contract to sell
(including, without limitation, any short sale), grant any option to purchase or
otherwise transfer or dispose of (other than to donees who agree to be similarly
bound) any securities of the Company held by it at any time during such period
except any Common Stock included in such registration; provided, however, that:

              (a) Such period shall not exceed one hundred eighty (180) days for
the first such registration statement of the Company which covers Common Stock
(or other securities) to be sold on its behalf to the public in an underwritten
offering;



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              (b) Such period shall not exceed ninety (90) days for any
subsequent registration statement of the Company which covers Common Stock (or
other securities) to be sold on its behalf to the public in an underwritten
offering; and

              (c) Nortel shall not be so obligated unless all executive officers
and directors of the Company are subject to or obligated to enter into similar
agreements.

              In order to enforce this Section 1.13, the Company may impose
stop-transfer instructions with respect to the Registrable Securities of Nortel
(and the shares or securities of any other person subject to the foregoing
restriction) until the end of such period. The obligations described in this
Section 1.12 shall not apply to a registration statement relating solely to
employee benefit plans on Form S-l or Form S-8 or similar forms which may be
promulgated in the future, or a registration statement relating solely to an SEC
Rule 145 transaction on Form S-4 or any similar form which may be promulgated in
the future.

                                    SECTION 2

                                  MISCELLANEOUS

         2.1 Governing Law. This Agreement shall be governed by and construed
under the laws of the State of California as applied to agreements among
California residents made and to be performed entirely with the State of
California.

         2.2 Entire Agreement; Amendment. This Agreement constitutes the full
and entire understanding and agreement between the parties with respect to the
subject matter hereof. This Agreement may be amended, waived, discharged or
terminated only by written consent of the Company and Nortel.

         2.3 Notices. Any notice, request or other communication required or
permitted hereunder shall be given in writing and shall be deemed to have been
duly given if personally delivered or if mailed by registered or certified mail,
postage prepaid, at the following addresses:

         If to the Company:            Applied Digital Access, Inc.
                                       9855 Scranton Road
                                       San Diego, California 92121
                                       Attn:  President

                                       Telephone No.:   (619) 623-2200
                                       Facsimile No.:   (619) 623-2208



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         With a copy to:               Brobeck, Phleger & Harrison LLP
                                       550 West C Street, Suite 1300
                                       San Diego, California 92101
                                       Attn: Faye H. Russell, Esq.

                                       Telephone No.:   (619) 234-1966
                                       Facsimile No.:   (619) 234-3848

         If to Nortel:                 Northern Telecom Limited
                                       Suite 100
                                       8200 Dixie Road
                                       Brampton, Ontario
                                       L6T 5P6
                                       Attn:    Corporate Secretary and
                                                Assistant General Counsel

                                       Telephone No.:   (905) 863-1103
                                       Facsimile No.:   (905) 863-8386

         Any party hereto may by notice so given change its address for future
notices hereunder. Notice shall conclusively be deemed to have been given when
personally delivered or when deposited in the mail in the manner set forth above
and shall be deemed to have been received when delivered.

         2.4 Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

         2.5 Severability. In the event that any provision of this Agreement
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Agreement shall continue in full force and effect
without said provision.

         2.6 Captions. The captions and headings to Sections and paragraphs of
this Agreement have been inserted for identification and reference purposes only
and shall not be used to construe the meaning or the interpretation of this
Agreement.


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                                      -12-


   13
         IN WITNESS WHEREOF, this Agreement has been duly executed and delivered
by the parties as of the date first above written.



APPLIED DIGITAL ACCESS, INC.,          NORTHERN TELECOM LIMITED,
a California corporation               a Canadian corporation



By:    /s/  JAMES L. KEEFE            By:
    -------------------------------        -------------------------------------
       James L. Keefe                  Its:
       Chief Financial Officer              ------------------------------------
                                       By:
                                           -------------------------------------
                                       Its:
                                            ------------------------------------

















             [SIGNATURE PAGE TO 1997 REGISTRATION RIGHTS AGREEMENT]