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                                                                 EXHIBIT 10.15.1

                     CUMMINGS PROPERTIES MANAGEMENT, INC.
                                 STANDARD FORM
                               COMMERCIAL LEASE

  In consideration of the covenants herein contained, Cummings Properties
Management, Inc., hereinafter called LESSOR, does hereby lease to
Radio Telephone Systems, Inc. (a MA corp.), One McKinley Square, Boston, MA
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02109 hereinafter called LESSEE, the following described premises, hereinafter
-----
called the leased premises: approximately 8,913 square feet at 100 Sylvan Road,
                            ---------------------------------------------------
Woburn, MA 01801 Suite 400 TO HAVE AND HOLD the leased premises for a term of
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five (5) years commencing at noon on March 1, 1996 and ending at noon on
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February 38, 2001 unless sooner terminated as herein provided. LESSOR and LESSEE
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now covenant and agree that the following terms and conditions shall govern this
lease during the term hereof and for such further time as LESSEE shall hold the
leased premises.

1.   RENT.  LESSEE shall pay to LESSOR base rent at the rate of one hundred six
                                                                ---------------
thousand five hundred ten (106,510.00) U.S. dollars per year, drawn on a U.S.
--------------------------------------
bank, payable in advance in monthly installments of $8,875.83 on the first day
                                                    ---------
in each calendar month in advance, the first monthly payment to be made upon
LESSEE's execution of this lease, including payment in advance of appropriate
fractions of a monthly payment for any portion of a month at the commencement or
end of said lease term. All payments shall be made to LESSOR or agent at 200
West Cummings Park, Woburn, Massachusetts 01001, or at such other place as
LESSOR shall from time to time in writing designate. If the "Cost of Living" has
increased as shown by the Consumer Price Index (Boston Massachusetts, all Items,
all urban consumers), U.S. Bureau of Labor Statistics, the amount of base rent
due during each calendar year of this lease and any extensions thereof shall be
annually adjusted in proportion to any increase in the Index. All such
adjustment shall take place with the rent due on January 1 of each year during
the lease term. The base month from which to determine the amount of each
increase in the Index shall be January 1996, which figure shall be compared with
                                         --
the figure for November 1996, and each November thereafter to determine the
                          --
percentage increase (if any) in the base rent to be paid during the following
calendar year. In the event that the Consumer Price Index as presently computed
is discontinued as a measure of "Cost of Living" changes, any adjustment shall
then be made on the basis of a comparable index than in general use.

2.   SECURITY DEPOSIT.  LESSEE shall pay to LESSOR a security deposit in the
amount of seventeen thousand (17,000.00) dollars upon the execution of this
          ------------------------------
lease by LESSEE, which shall be held as security for LESSEE's performance as
herein provided and refunded to LESSEE without interest at the end of this lease
subject to LESSEE's satisfactory compliance with the conditions hereof. LESSEE
may not apply the security deposit to payment of the last month's rent, in the
event of any default or breach of this lease by LESSEE, LESSOR shall immediately
apply the security deposit first to any unamortized improvements completed for
LESSEE's occupancy, then to offset any outstanding invoice or other payment due
to LESSOR, with the balance applied to outstanding rent. If all or any portion
of the security deposit is applied to cure a default or breach during the term
of the lease. LESSEE shall be responsible for restoring said deposit forthwith
and failure to do so shall be considered a substantial default under the lease.
LESSEE's failure to remit the full security deposit or any portion thereof when
due shall also constitute a substantial lease default.

3.   USE OF PREMISES. LESSEE shall use the leased premises only for the purpose
of executive and administrative offices.
   ------------------------------------

4.   ADDITIONAL RENT.  LESSEE shall pay to LESSOR as additional rent a
proportional share (based on square footage leased by LESSEE as compared with
the total leaseable square footage of the building of which the leased premises
are a part) of any increase in the real estate taxes levied against the land and
building of which the leased premises are a part, whether such increase is
caused by an increase in the tax rate, or the assessment on the property, or a
change in the method of determining real estate taxes. LESSEE shall make payment
within thirty days (30) of written notice from LESSOR that such increased taxes
are payable, and any additional rent shall be prorated should the lease
terminate before the end of any tax year. In the event that said building was
not assessed as a complete building as of the aforementioned date, then the base
assessment shall be as of the first date when the building is assessed as a
complete structure.

5.   UTILITIES.  LESSOR shall provide equipment per LESSOR's building standard
specifications to heat the leased premises in season and to cool all office
areas between May 1 and November 1. LESSEE shall pay all charges for heat and
electricity used on the leased premises.* LESSEE shall pay LESSOR for all water
and sewer use as determined by a separate water meter serving the leased
premises, and LESSEE shall pay LESSOR a proportionate share of any other fees
and charges relating in any way to water or sewer use at the building. No
plumbing, construction or electrical work of any type shall be done without
LESSOR's prior written approval and the appropriate municipal permit.

6.   COMPLIANCE WITH LAWS. LESSEE acknowledges that no trade, occupation,
activity or work shall be conducted in the leased premises or use made thereof
which may be unlawful, improper, noisy, offensive, or contrary to any applicable
statute, regulation, ordinance or bylaw. LESSEE shall keep all employees working
in the leased premises covered with Worker's Compensation Insurance and shall
obtain any licenses and permits necessary for LESSEE's occupancy. LESSEE shall
be responsible for causing the leased premises and any alterations by LESSEE
which are allowed hereunder to be in full compliance with any applicable
statute, regulation, ordinance or bylaw.

7.   FIRE, CASUALTY, EMINENT DOMAIN. Should a substantial portion of the leased
premises, or of the property of which they are a part, be substantially damaged
by fire or other casualty, or be taken by eminent domain, LESSOR may elect to
terminate this lease. When such fire, casualty, or taking renders the leased
premises substantially unsuitable for their intended use, a just and
proportionate abatement of rent shall be made, and LESSEE may elect to terminate
this lease if: (a) LESSOR fails to give written notice within thirty (30) days
of intention to restore the leased premises, or (b) LESSOR fails to restore the
leased premises to a condition substantially suitable for their intended use
within ninety (90) days of said fire, casualty or taking. LESSOR reserves all
rights for damages or injury to the leased premises for the taking by eminent
domain, except for the damage to LESSEE's property or equipment.

5. *as determined by separate meters serving the leased premises.

<PAGE>

  27. GENERAL (a) The invalidity or unenforceability of any provision of this
lease shall not affect or render invalid or unenforceable any other provision
hereof. (b) The obligations of this lease shall run with the land, and this
lease shall be binding upon and inure to the benefit of the parties hereto and
their respective successors and assigns, except that LESSOR and OWNER shall be
liable only for obligations occurring while lessor, owner, or master lessee of
the premises. (c) Any action or proceeding arising out of the subject matter of
this lease shall be brought by LESSEE within one year after the cause of action
has occurred and only in a court of the Commonwealth of Massachusetts. (d) If
LESSOR is acting under or as agent for any trust or corporation, the obligations
of LESSOR shall be binding upon the trust or corporation, but not upon any
trustee, officer, director, shareholder, or beneficiary of the trust or
corporation individually. (e) If LESSOR is not the owner (OWNER) of the leased
premises, LESSOR represents that said OWNER has agreed to be bound by the terms
of this lease unless LESSEE is in default hereto. (f) This lease is made and
delivered in the Commonwealth of Massachusetts, and shall be interpreted,
construed, and enforced in accordance with the laws thereof. (g) This lease was
the result of negotiations between parties of equal bargaining strength, and
when executed by both parties shall constitute the entire agreement between sold
parties. No other oral or written representation shall have any effect hereon,
and this agreement may not be altered, extended or amended except by written
agreement attached hereto or as otherwise provided herein. (h) Notwithstanding
any other statements herein, LESSOR makes no warranty, express or implied,
                             --------------------------------------------
concerning the suitability of the leased premises for LESSEE's intended use. (i)
LESSEE agrees that if LESSOR does not deliver possession of the leased premises
as herein provided for any reason, LESSOR shall not be liable for any damages to
LESSEE for such failure, but LESSOR agrees to use reasonable efforts to deliver
possession to LESSEE at the earliest possible date, and a proportionate
abatement of rent for such time as LESSEE may be deprived of possession said
leased premises shall be LESSEE's sole remedy. (j) Neither the submission of
this lease form, nor the prospective acceptance of the security deposit and/or
rent shall constitute a reservation of or option for the leased premises, or any
offer to lease, it being expressly understood and agreed that this lease shall
not bind either party in any manner whatsoever until it has been executed by
both parties. (k) LESSEE shall not be entitled to exercise any option contained
herein if LESSEE is in default of any forms or conditions hereof. (l) The
headings in this lease are for convenience only and shall not be considered part
of the terms hereof. (m) No endorsement by LESSEE on any check shall bind LESSOR
in any way.

  28. SECURITY AGREEMENT. LESSEE hereby grants LESSOR a continuing security
interest in all existing or hereafter acquired property of LESSEE which is in
the leased premises to secure the payment of rent, the cost of leasehold
improvements, and the performance of any other obligations of LESSEE under this
lease. Default in the payment or performance of any of LESSEE's obligations
hereunder is a default under this Security Agreement, and shall entitle LESSOR
to immediately exercise all of the rights and remedies of a Secured Party under
the Uniform Commerical Code. LESSEE also agrees to execute a UCC-1 Financing
Statement and any other financing agreement required by LESSOR in connection
with this security interest.

  29. WAIVERS, ETC. No consent or waiver, express or implied, by LESSOR, to or
of any breach of any covenant, condition or duty of LESSEE shall be construed as
a consent or waiver to or of any other breach of the same or any other covenant,
condition or duty. If LESSEE is several persons, several corporations or a
partnership, LESSEE's obligations are joint or partnership and also several.
Unless repugnant to the context, "LESSOR" and "LESSEE" mean the person or
persons, natural or corporate, named above as LESSOR and as LESSEE respectively,
and their respective heirs, executors, administrators, successors and assigns.

  31. ADDITIONAL PROVISIONS. (Continued on attached rider if necessary._


                             - See Attached Rider-




IN WITNESS WHEREOF, LESSOR AND LESSEE have hereunto set their hands and common
seals and intend to be legally bound hereby this 29th day of February
1996.

LESSOR: CUMMINGS PROPERTIES MANAGEMENT, INC.    LESSEE: RADIO TELEPHONE SYSTEMS,
INC.

     By: /s/ James McKeown                  By: /s/ Robert J. Sullivan
        --------------------------------       ------------------------------


                                   GUARANTY

IN CONSIDERATION of the making of the above lease by Cummings Properties
Management, Inc. with Radio Telephone Systems, Inc.
                      ---------------------------------------------------------
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at the request of the undersigned and in reliance of this guaranty, the
undersigned (GUARANTOR) hereby personally guarantees the prompt payment of rent
by LESSEE and the performance by LESSEE of all terms, conditions, covenants and
agreements of the lease, any amendments (hereto and any extensions or
assignments thereof, and the undersigned promises to pay all expenses, including
reasonable attorney's fees, incurred by LESSOR in enforcing all obligations of
LESSEE under the lease or incurred by LESSOR in enforcing this guaranty.
LESSOR's consent to any assignments, subleases, amendments and extensions by
LESSEE or to any compromise or release of LESSEE's liability hereunder, with or
without notice to the undersigned, or LESSOR's failure to notify the undersigned
of any default and/or reinstallment of the lease by LESSEE, shall not relieve
the undersigned from liability as GUARANTOR.

IN WITNESS WHEREOF, the undersigned GUARANTOR has hereunto set his/her/its hand
and common seal intending to be legally bound hereby this ____ day of _______
19__.


                                               X _______________________________
<PAGE>

                                 STANDARD FORM
                                RIDER TO LEASE


The following additional provisions are incorporated into and made a part of the
attached lease.

A.   * With reference to Section 15 hereinabove, LESSEE shall include LESSOR and
     OWNER on LESSEE's comprehensive general liability policy as additional
     insureds using standard endorsement 150 Form CO 20 26 11 85 or another form
     approved in advance by LESSOR.

B.   LESSOR at LESSEE's expense of $6,500.00 to be paid by LESSEE upon execution
     of this lease, shall construct standard open office space in the
     approximately 5,000 square foot area marked "Space A" on the mutually
     agreed upon plan attached hereto before or about the time LESSEE takes
     possession of the leased premises.

C.   In addition, LESSOR at LESSOR's expense shall construct standard office
     space within the established area marked "Space B" within sixty (60) days
     of a mutually agreed upon plan for said Space B with equivalent or less
     office partitioning as shown on the attached preliminary plan. Said space
     shall be air conditioned for normal office use, carpeted and completed with
     painted drywall partitions, acoustical tile ceilings, recessed lighting,
     chrome pendent fire protection sprinklers, and 110V convenience electrical
     wall outlets at regular intervals. Notwithstanding the delayed completion
     date of "Space D." LESSEE's obligation to pay rent hereunder for the entire
     leased premises shall commence as of March 1, 1996 or upon substantial
     completion of the modifications described in Paragraph B above for "Space
     A," whichever is later.

D.   * Notwithstanding monthly rent as provided in Section 1 herein, LESSEE may
     deduct $4,892.53 per month from each monthly rental payment due from March
     1, 1996 through May 30, 1996 (only) provided LESSOR resolves each such
     monthly payment on or before the first day of the month for which that rent
     is due and LESSEE is not otherwise in default of the lease or in arrears of
     any rent or invoice payment. Time is of the essence.

E.   * LESSEE shall have access to the leased premises seven (7) days per week,
     twenty-four (24) hours per day. LESSEE acknowledges and agrees that LESSOR
     has no responsibility for providing any security services for the leased
     premises, and LESSEE assumes any and all risks arising out of this
     unlimited access provision.

F.   * The maximum, cumulative "Cost of Living" interest during the initial
     term of the lease (only) shall not exceed an average of five percent (5%)
     per calendar year.

G.   * In the event this lease is terminated and LESSEE pays LESSOR accelerated
     rent in accordance with the provisions of Section 19 herein, LESSOR agrees
     to make reasonable efforts to re-let the leased premises and otherwise
     mitigate its damages resulting from such termination. LESSOR shall credit
     LESSEE for any rents actually received by LESSOR over the balance of the
     lease term minus any costs incurred by LESSOR in re-letting the premises.
     LESSOR's failure to re-let the leased premises despite LESSOR's reasonable
     efforts shall not limit LESSEE's liability hereunder.

H.   * LESSEE shall have the right to assign this lease or sublet the leased
     premises to an affiliated corporation, namely a corporation in which LESSEE
     owns at least fifty percent interest, which owns at least a fifty percent
     interest in LESSEE, with which LESSEE merges or which is formed as a result
     of a merger or consolidation involving LESSEE, without further consent from
     LESSOR, provided LESSEE so notifies LESSOR in writing to that effect on a
     timely basis. The provisions of Section 10 shall govern said assignment in
     all other respects.

I.   * Provided LESSEE is not then in default of this lease or in arrears of any
     rent or invoice payment, LESSEE shall have the right to extend this lease,
     including all terms, conditions, extensions, etc., for one additional
     period of five (5) years ("the extended lease term") by serving LESSOR with
     written notice of its desire to so extend the lease. The time for serving
     such written notice shall be not more than twelve (12) months or less than
     six (6) months prior to the expiration of the initial lease term. Time is
     of the essence.

J.   The base rent during the extended lease term shall be the lesser of the
     following: (1) the adjusted have rent provided in Section 1, plus all "Cost
     of Living" adjustments through January 1, 2001 in accordance with Section
     1; or (2) LESSOR's published annual rental rate for similar office space as
     of January 1, 2001 times the number of square feet leased. The base month
     from which to determine the amount of each "Cost of Living" adjustment
     during the extended lease term shall be changed to January 2001, the
     "comparison" month shall be changed to November 2001, and the first
     adjustment during the extended lease term shall take place with the rent
     due on January 1, 2002. Section 1 shall continue to apply in all other
     respects during the extended lease term.

K.   Consistent with LESSOR's usual efforts to accommodate the growth and
     expansion of existing tenants, prior to initial leasing to others, LESSOR
     shall endeavor to keep LESSEE informed of the status of interest by others
     in the presently vacant space which is continuous to and on the same floor
     as the leased premises. It is specifically understood, however, that said
     space is available on a "first come, first served" basis and that LESSOR's
     failure to inform or notify LESSEE prior to leasing said space or any
     portion thereof to others shall not in any way constitute a default or
     breach of LESSOR's obligations under this lease and shall not impose any
     liability on LESSOR.


LESSOR: CUMMINGS PROPERTIES MANAGEMENT, INC.


  By: /s/ James McKeown
     ---------------------------------------
                                   President

  Date:   February 29, 1996
       -------------------------------------


LESSEE: RADIO TELEPHONE SYSTEMS, INC.


  By: /s/ Robert J. Sullivan
     ---------------------------------------