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                                                                    EXHIBIT 10.7

C                       SECOND AMENDMENT TO LEASE AGREEMENT

        This Second Amendment to Lease Agreement ("Second Amendment") is made as
of this 25th day of March, 1996 by and between Teachers Realty Corporation
("Landlord") and Voicetek Corporation ("Tenant").

        WHEREAS, Landlord and Tenant have heretofore executed a certain Lease
Agreement dated May 25, 1993, which Lease Agreement has been amended by that
certain First Amendment to Lease Agreement (the "First Amendment") dated August
8, 1994 (said Lease Agreement as amended by the First Amendment is hereafter the
"Lease") pursuant to which Tenant has leased 33,500 rentable square feet of area
(comprised of the 19,881 square foot "Original Premises" originally leased to
Tenant under the Lease Agreement and the 13,619 square foot "New Premises"
demised to Tenant under the First Amendment) in a building (the "Building")
known as 19 Alpha Road, Chelmsford, MA; and

        WHEREAS, Landlord and Tenant have agreed to further expand the Premises
on two occasions so that Tenant shall lease (i) an additional 3,520 rentable
square feet of area (the "Second Expansion Space") and (ii) an additional 13,700
rentable square feet of area (the "Third Expansion Space"), all as more
particularly shown on Exhibit A to this Second Amendment subject to the terms,
covenants and provisions of the Lease as amended hereby; and

        WHEREAS, the Initial Term of the Lease (as extended by the First
Amendment) is scheduled to expire on October 31, 1999; and

        WHEREAS, Landlord and Tenant have agreed to enter into this Second
Amendment in order to memorialize their agreements and to otherwise modify and
amend the Lease to (i) reflect the increases in the size of the Premises demised
under the Lease from time to time as a result of the addition of the Second
Expansion Space and the Third Expansion Space and (ii) to otherwise modify and
amend the Lease as hereinafter set forth.

        NOW, THEREFORE, in consideration of Ten ($10.00) Dollars and other good
and valuable consideration, the receipt and sufficiency of which are
acknowledged, Tenant and Landlord hereby agree as follows:

1. Second Expansion Space; Changes in Basic Lease Provisions. Effective as of
March 25,1996 (the "Second Expansion Commencement Date"), the information
provided in Article I of the Lease captioned "Basic Lease Provisions" (as
previously amended) will be changed and the Lease shall be deemed amended in the
following respects:

         (a) The definition of the term "Premises Rentable Area" shall be
amended by deleting the reference to "33,500 rentable square feet" and inserting
in its place and stead the number "37,020 rentable square feet".

                                                      
                                                      
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         (b) The definition of the term "Basic Rent" shall be amended by
inserting the phrase "plus the Second Expansion Rent" after the numbers set
forth in the "Basic Rent" and "Monthly Payment" columns of paragraph 1(b) B.
and 1(b) C. of the First Amendment.

         As used herein, the term "Second Expansion Rent" shall mean (a) for the
period beginning on the Second Expansion Commencement Date and ending on October
31, 1996, $15,136.00 per annum ($4.30 per square foot contained in the Second
Expansion Space) payable in equal monthly installments of $1,261.33 (pro rated
for any partial month in which the Second Expansion Commencement Date shall
fall) and (b) for the period beginning on November 1, 1996 through the last day
of Initial Term (October 31, 1999) the amount of $15,840.00 per annum ($4.50 per
square foot contained in the Second Expansion Space) payable in equal monthly
installments of $1,320.00. All such Second Expansion Rent shall be payable on
the first day of each calendar month (pro rated as of the Second Expansion
Commencement Date as aforementioned) without deduction, offset, abatement or
demand.

         In addition to the increases in the Basic Rent as it is amended by the
provisions of paragraphs 1(b) and 4(b) of this Second Amendment, Tenant shall
continue to make the monthly payments of the Reimbursement Rent as defined under
Article III, Section 3.1(c) of the Lease as and when required by the terms of
said Section 3.1(c) of the Lease and these payments of Reimbursement Rent shall
remain unchanged by this Second Amendment.

         (c) The definition of the term "Security Deposit" shall be amended and
increased in the amounts described in paragraph 7 of this Second Amendment.

         (d) The definition of the term "Building Rentable Area" shall be deemed
amended by deleting "64,250 rentable square feet" and inserting in its place and
stead "63,220 rentable square feet".

         (e) The definition of the term "Escalation Factor" shall be amended by
deleting "54.88%" and inserting the number "61.64%" in its place and stead.

2. Second Expansion Space Expansion; Generally. Effective as of the Second
Expansion Commencement Date, the Second Expansion Space shall be deemed added to
and included in the Premises demised under the Lease for the balance of the Term
of this Lease and, until the Third Expansion Commencement Date, the term
"Premises" wherever used in the Lease shall be deemed to mean and include the
Second Expansion Space together with the Original Premises and the New Premises.
Accordingly, monthly and annual payments on account of Escalation Charges shall
be increased to reflect the increase in the size of the Premises resulting from
the addition of the Second Expansion Space.

3. Landlord's Second Expansion Work Deemed Completed. It is agreed and
understood that the provisions of Article IV of the Lease and paragraph 4 of the
First

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Amendment shall not be applicable to the Second Expansion Space and Landlord
shall have no obligation whatsoever to perform the work described therein.

         Tenant hereby acknowledges and agrees that Landlord has, as of the date
of this Second Amendment, completed the work described in Exhibit B to this
Second Amendment ("Landlord's Second Expansion Work").

         Tenant hereby approves all work performed by Landlord in the Second
Expansion Space. Accordingly, the Second Expansion Space is being leased in its
condition as of the date of this Second Amendment, "as is" without warranty or
representation by Landlord. Tenant acknowledges that it has inspected the Second
Expansion Space and Landlord's Second Expansion Work and has found the same to
be satisfactory and complete.

4.       Third Expansion Space; Changes in Basic Lease Provisions. Effective as
of the Third Expansion Commencement Date (as hereinafter defined), the
information provided in Article I of the Lease captioned "Basic Lease
Provisions" (as previously amended) will be changed and the Lease shall be
deemed amended in the following respects:

         (a) The definition of the term "Premises Rentable Area" (as amended by
paragraph 1 of this Second Amendment) shall be amended by deleting the reference
to "37,020 rentable square feet" and inserting in its place and stead the number
"50,720 rentable square feet".

         (b) The definition of the term "Basic Rent" shall be amended by
inserting the phrase "and the Third Expansion Rent" (in addition to the phrase
"plus the Second Expansion Rent" after the numbers set forth in the Basic Rent
and Monthly Payment columns of paragraph 1(b) B. and 1(b) C. of the First
Amendment (as they have been amended by paragraph 1(b) of this Second
Amendment).

         As used herein, the term "Third Expansion Rent" shall mean (a) for the
period beginning on the Third Expansion Commencement Date and ending on the last
day of the calendar month in which the first (1st) anniversary of the Third
Expansion Commencement Date shall fall, $95,900.00 ($7.00 per rentable square
foot contained in the Third Expansion Space) payable in equal monthly
installments of $7,991.67 (pro rated for any partial calendar month in which the
Third Expansion Commencement Date should fall), (b) for the twelve (12) calendar
month period immediately following the period described in (a) above, $99,325.00
per annum ($7.25 per rentable square foot contained in the Third Expansion
Space) payable in equal monthly installments of $8,277.08, and (c) for the
period commencing immediately following the period described in (b) above and
thereafter for the remainder of the Initial Term (October 31, 1999), $102,750.00
per annum ($7.50 per rentable square foot contained in the Third Expansion
Space) payable in equal monthly installments of $8,562.50. All such Third
Expansion Rent shall be payable on the first day of each calendar month (pro
rated as of the Third Expansion Commencement Date as aforementioned) without
deduction, offset, abatement or demand.

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         (c) The definition of the term "Escalation Factor" shall be amended by
deleting "61.64%" (as increased and adjusted by the provisions of paragraph 1(e)
of this Second Amendment") and inserting the number "84.45%" in its place and
stead.

5.       Third Expansion Space Expansion; Generally. Effective as of the Third
Expansion Commencement Date, the Third Expansion Space shall be added to and
included in the Premises demised under the Lease for the balance of the Term of
this Lease and the term "Premises" wherever used in the Lease shall be deemed to
mean and include the Third Expansion Space together with the Original Premises,
the New Premises and the Second Expansion Space. Accordingly, monthly and annual
payments on account of Escalation Charges shall be increased to reflect the
increase in the size of the Premises resulting from the addition of the Third
Expansion Space.

6.       Landlord's Third Expansion Work; Third Expansion Commencement Date.

6.1      Commencement Date. (a) The Third Expansion Commencement Date shall be
the earlier of (i) that date (the "Target Date") which is sixty (60) days after
the Delivery Date (as said term is hereafter defined) irrespective of whether
Tenant has completed Tenant's Work or obtained a Certificate of Occupancy, or
(ii) that date on which Tenant commences occupancy of the Third Expansion Space
for the Permitted Uses, whichever first occurs.

         Each of the parties hereto agrees, upon demand of the other, to execute
a declaration expressing the Third Expansion Commencement Date as soon as the
Third Expansion Commencement Date has been determined. As used herein, the term
"Delivery Date" shall mean that date upon which Landlord shall deliver
possession of the Third Expansion Space to Tenant as set forth in a written
notice from Landlord to Tenant (a "Delivery Notice"). The Delivery Date shall
not occur until Landlord and Tenant have each executed and delivered this Second
Amendment and all existing tenants of any portion of the Third Expansion Space
(if any there may be) have vacated the Third Expansion Space.

6.2      Tenant's Third Expansion Plans.

         (a) Tenant hereby agrees to accept the Third Expansion Spaces in its
"as is" condition on the Delivery Date, with all faults and without
representation or warranty by Landlord of any kind. All work, construction and
improvements to be performed in the Third Expansion Space for use and occupancy
by Tenant shall be provided and installed by Tenant at Tenant's sole cost and
expense (subject to Landlord's obligation to fund the Allowance in accordance
with the provisions of this Paragraph 6). Prior to commencement of any work by
Tenant, Tenant shall deliver to Landlord a detailed floor plan layout together
with detailed construction drawings, detailed specifications and written
instructions (herein called "Tenant's Third Expansion Plans") reflecting the
partitions, improvements, mechanical, electrical and other work and alterations
desired by Tenant in the Third Expansion Space. Landlord shall not unreasonably
withhold or delay its approval of Tenant's Third Expansion Plans.

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6.3      Tenant's Work.

         (a) Landlord's approval of Tenant's Third Expansion Plans and
specifications shall, in no event, unless expressly set forth in such approval,
be deemed to create any obligation on the part of Landlord to do any work or
make any installations in or about the Third Expansion Space nor to authorize
Tenant to make any further additions, improvements or alterations to the Third
Expansion Space. Tenant shall be responsible for the construction of all work
and improvements necessary for Tenant to occupy the Third Expansion Space.
Without limitation of the foregoing, Tenant shall be responsible for completing
(at Tenant's sole cost and expense) all work necessary to separately meter
utilities used and consumed in the Third Expansion Space (to the extent not
already separately metered) and shall arrange for such services directly with
the applicable utilities. All utilities used or consumed in the Premises during
performance of Tenant's Third Expansion Work shall also be the responsibility of
Tenant.

         (b) Tenant shall perform, at its sole cost and expense, all of the work
(the "Tenant's Third Expansion Work") shown on Tenant's Third Expansion Plans
strictly in accordance with Tenant's Third Expansion Plans. Any changes to
Tenant's Third Expansion Plans shall be subject to the approval of Landlord
which approval will not be unreasonably withheld or delayed. Tenant's Third
Expansion Work shall be performed by Tenant strictly in compliance with and
subject to the provisions of Section 5.2 of the Lease. Without limitation of
Landlord's rights to approve all aspects of Tenant's Third Expansion Work and
Tenant's Third Expansion Plans, Landlord hereby approves the location of the
windows shown on that certain Space Plan by King Design Associates, Inc. dated
June 5, 1996. Notwithstanding the foregoing to the contrary, Landlord hereby
expressly reserves the right to review and approve any structural changes to the
Building necessary to effect installation of such windows, the actual materials
and windows used and the appearance and aesthetic impact on the Building
resulting from the installation of such windows. In addition to and without
limitation of any other provision of this Lease, Landlord hereby reserves the
right to require that Tenant, at its sole cost and expense, remove such windows
from the Building upon expiration or earlier termination of this Lease. If
Landlord shall elect to require that Tenant remove such windows as aforesaid,
Tenant hereby agrees to remove same and restore the Building to its condition
prior to installation of such windows. The provisions of this paragraph (b)
shall survive expiration or earlier termination of the Term of this Lease.

         (c) Prior to commencing occupancy of all or any portion of the Third
Expansion Space, Tenant shall, at its sole expense, procure a Certificate of
Occupancy and any other permit or approval required by the Town of Chelmsford or
the Commonwealth of Massachusetts for its use and occupancy of the Third
Expansion Space and Tenant shall deliver copies thereof to Landlord. Subject to
all applicable provisions of this Lease, entry of the Third Expansion Space by
Tenant or its agents or contractors prior to the Third Expansion Commencement
Date for the limited purpose of performing Tenant's Third Expansion Work shall
be permitted. In no event shall the Third Expansion Commencement Date be delayed
by reason of Tenant's failure to complete the Tenant's

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Third Expansion Work prior to the Target Date. Tenant shall not damage or deface
the Building or any part thereof in connection with the Tenant's Third
Expansion Work and Tenant shall promptly reimburse Landlord for the cost of
repairing any damage to the Building caused by Tenant, its employees, workmen,
contractors, subcontractors, materialmen and all other parties who are involved
in performing all or any part of Tenant's Third Expansion Work.

         Tenant shall, at its sole cost and expense, cause Tenant's Third
Expansion Work to be guaranteed and bonded for completion. Tenant hereby agrees
that Tenant's Third Expansion Work shall be completed in accordance with
Tenant's Third Expansion Plans first approved by Finard & Company, Inc.
("Landlord's Construction Representative").

         To the maximum extent this Agreement may be made effective according to
law, Tenant agrees to indemnify, defend and save Landlord harmless from and
against any and all loss, cost, penalties, liabilities, damages and claims
arising from any act, omission or negligence of Tenant or Tenant's General
Contractor or any contractors or workman employed by either of them ("Tenant's
Subs") or their respective contractors, licensees, agents, servants or employees
arising from the performance of Tenant's Third Expansion Work caused to any
person or to the property of any person, the Building, or the Property. This
indemnity shall, to the maximum extent this agreement may be made effective
according to law, also extend to all loss, cost, penalties, liability, damage,
claims or whatever nature asserted against the Landlord arising out of the use
or occupancy or passage or travel over or upon, the Property by Tenant or by any
person claiming by, through or under Tenant including, without limitation,
Tenant's General Contractor and Tenant's Subs and their respective agents,
employees and contractors and customers or arising out of any delivery to or
service applied to the Third Expansion Space or the Building or on account of or
based on anything whatsoever done on the Property. The indemnities contained in
this paragraph shall (i) include indemnity against all cost, expenses and
liabilities incurred in or in connection with any such claim or proceeding
brought thereon and the defense thereof with counsel approved by the Landlord
and (ii) survive expiration or earlier termination of this Lease.

6.4      Landlord's Allowance; Payment.

         (a) Landlord shall make a dollar contribution (hereafter the
"Allowance") toward the cost of completing Tenant's Work (including, without
limitation, labor, materials, construction supervision, permitting,
architectural fees and engineering fees) in an amount not to exceed Eighty Two
Thousand Two Hundred and No/100ths ($82,200.00) Dollars. The total cost of the
Tenant's Work in excess of the amount of the Allowance (such excess costs being
hereafter the "Excess Costs") shall be borne by Tenant. The Allowance shall not
be applied to payment for office furniture or equipment or related expenses.

         (b) Payment. Provided that no Default of Tenant shall exist and be
continuing, periodically, but not more than once per calendar month and within
thirty (30) days after (i) Tenant's General Contractor or Tenant has submitted
to Landlord's Construction Representative approved applications or invoices for
Tenant's Third Expansion Work

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performed and completed and materials in place during such period on Standard
AIA Requisition Forms with appropriate line item break-downs (a "Requisition")
and (ii) delivery to Landlord of appropriate partial lien waivers from Tenant's
General Contractors which includes subcontractors' invoices for Tenant's Third
Expansion Work performed to date and appropriate partial lien waivers from
Tenant's Subs on Lien Waiver forms acceptable to Landlord's Construction
Representative and (iii) in each case, a certification from Tenant's Architect 
certifying as to the state of completion of such work and installation of such
materials, Landlord shall pay to Tenant's General Contractor out of the
Allowance, the cost of the Tenant's Third Expansion Work performed to date as
shown on the Requisition (subject to the usual 10% retainage). No sooner than
thirty (30) days after the Commencement Date and after Tenant has submitted to
Landlord (i) the final Requisition, (ii) appropriate final lien waivers from
Tenant's General Contractor which includes final subcontractors' invoices and
appropriate final lien waivers from Tenant's Subs, (iii) a Certificate from
Tenant and Tenant's Architect that the Tenant's Third Expansion Work has been
completed in compliance with Tenant's Third Expansion Plans and (iv) upon
acceptance of Tenant's Third Expansion Work by Landlord, Landlord shall pay the
amount of the final Requisition from the Allowance, if any amounts are so
available. It is agreed and understood that Landlord's contribution toward the
total cost of Tenant's Third Expansion Work shall not exceed the Allowance. All
costs and expenses incurred in connection with Tenant's Third Expansion Work in
excess of the Allowance shall be borne by Tenant. Landlord shall be entitled to
retain any portion of the Allowance not needed to complete Tenant's Third
Expansion Work.

        Tenant shall not permit any mechanics' lien, materialmen's lien, or any
other lien to be filed against the Premises, the Building, the Property or
Landlord by reason of Tenant's Third Expansion Work or by reason of any other
work performed by Tenant, Tenant's General Contractor or Tenant's Subs or
suppliers. Tenant shall indemnify and hold Landlord wholly harmless from and
against all loss, cost, expense, liability and damage resulting from any failure
of Tenant to pay for the Tenant's Third Expansion Work including, without
limitation, legal fees incurred in connection with such failure to pay.

6.5      Demolition Allowance.

         In addition to the Allowance, subject to the provisions hereof,
Landlord will bear the cost and expense of performing Demolition Work in the
Third Expansion Space in conjunction with the Third Expansion Work ("Demolition
Costs") up to the amount of the "Demolition Allowance" (as hereafter defined).
In no event shall Landlord be obligated to pay for any Demolition Costs in
excess of the Demolition Allowance (as said term is hereinafter defined). As
used herein, the term "Demolition Allowance" shall mean $18,500.00 ($1.35 per
rentable square foot) contained in the Third Expansion Space. Tenant shall pay
for all Demolition Costs in excess of the Demolition Allowance as and when
billed therefor. Landlord shall be entitled to retain any portion of the
Demolition Allowance not needed for Demolition Work necessary to prepare the
Third Expansion Space for Tenant's Third Expansion Work. The Demolition
Allowance will be disbursed

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in the same manner as applies to disbursements of the Allowance pursuant to
Section 6.4 hereof.

7. Security Deposit Increase. Effective as of the date of this Second Amendment,
the Security Deposit held by Landlord pursuant to the Lease shall be increased
by the additional amount of $23,240.00 representing increases in the Security
Deposit in the amount of (i) $2,640.00 with respect to the Second Expansion
Space and (ii) $20,600.00 with respect to the Third Expansion Space.
Accordingly, Tenant shall deposit the necessary additional amounts to be added
to the Security Deposit so that from and after the date of this Second
Amendment, the amount of the Security Deposit deposited with Landlord under the
Lease shall be in the aggregate amount of $55,606.12 and the definition of the
term "Security Deposit" shall be increased and adjusted to be $55,606.12 for all
purposes under the Lease. Such additional amounts as may be necessary to be
deposited with Landlord hereunder shall be paid to Landlord simultaneously with
the execution and delivery of this Lease.

8. No Brokers. Tenant warrants and represents that Tenant has dealt with no
broker in connection with the consummation of this Second Amendment and, in the
event of any brokerage claims against Landlord predicated upon prior dealings
with Tenant, Tenant agrees to defend the same and indemnify Landlord against any
such claim.

9. Capitalized terms used herein and not otherwise defined herein shall have the
meanings ascribed to them in the Lease. Except as herein modified, all terms,
covenants and provisions of the Lease are hereby ratified and affirmed.

WITNESS our hands and seals on the day and year first above written.

                                                     LANDLORD:
                                                     TEACHERS REALTY CORPORATION

                                                     By: /s/ Richard J. Usas
                                                        ------------------------

                                                     Its: Director
                                                         -----------------------

                                                     TENANT:
                                                     VOICETEK CORPORATION

                                                     By: /s/ Roger Tuttle
                                                        ------------------------
                                                     Its:
                                                         -----------------------

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                                   EXHIBIT A

                             [VOICETEK FLOOR PLAN]