Document:

<PAGE>

                                                                   Exhibit 10.13
                                                                   -------------

 Confidential Materials omitted and filed separately with the Securities and
               Exchange Commission. Asterisks denote omissions.

                            Switchboard Incorporated
                               115 Flanders Road
                         Westboro, Massachusetts 01581

                               December 6, 2000

Mr. Fredric G. Reynolds
Executive Vice President and
 Chief Financial Officer
Viacom Inc.
1515 Broadway
New York, New York 10036

      Re:   [**]

Dear Fred:

     Reference is made to the [**], dated as of December 6, 2000. In
consideration for Viacom Inc. agreeing to [**] contained in the [**]
Agreement (the"[**] Agreement") dated as of [**] by and among [**], Banyan
Systems Incorporated, and Switchboard Incorporated ("Switchboard"), and the
License Agreement (the "License Agreement" and together with the [**]
Agreement, the "[**]/Switchboard Agreements") dated as of [**] by and between
[**] and Switchboard, Switchboard agrees that [**] 250,000 [**].

                                             Respectfully yours,

                                             SWITCHBOARD INCORPORATED

                                             By: /s/ Dean Polnerow
                                                 -------------
                                                 Dean Polnerow
                                                 President<PAGE>

                                                                   Exhibit 10.27
                                                                   -------------

                                   SUBLEASE

     THIS SUBLEASE dated as of November 28, 2000 between ePresence, Inc. (the
"Sublandlord") and Switchboard, Inc. (the "Subtenant").

                                   ARTICLE I

                                REFERENCE DATA

     1.1  Subjects Referred To.
          --------------------

     Each reference in this Sublease to any of the following subjects shall be
construed to incorporate the data stated for that subject in this Section 1.1:

Date of Sublease:             November 28, 2000

Sublandlord:                  ePresence, Inc., a Massachusetts corporation

Sublandlord's Address:        120 Flanders Road, Westborough, Massachusetts

Subtenant:                    Switchboard, Inc., a Delaware corporation

Subtenant's Address:          115 Flanders Road, Westborough, Massachusetts

Headlandlord:                 Commonwealth Westborough Limited Partnership

Headlandlord's Address:       c/o J. F. White Properties, Inc.
                              One Gateway Center, Suite 500
                              Newton, MA 02158

Headlease:                    Lease Agreement dated as of April 21, 1989 by and
                              between CB-Westboro C Limited Partnership, as
                              landlord, and Sublandlord, as tenant, as amended
                              by a Lease Addendum dated December 31, 1991, a
                              Second Lease Addendum dated April 1, 1993, a Third
                              Lease Addendum dated July 22, 1994, and a Fourth
                              Lease Addendum dated September 19,1995.
                              Commonwealth Westborough Limited Partnership is
                              the successor in interest to CB-Westboro C Limited
                              Partnership.

Headleased Premises:          The premises situated at 120 Flanders Road,
                              Westborough, Massachusetts, as described in the
                              Headlease, containing approximately 79,203
                              rentable square feet (constituting all of the
                              rentable square feet in the building) (the
                              "Building").

Premises:                     The Premises are shown on Exhibit B attached
                              hereto.

Rentable Floor Area           17,976 Rentable Square Feet on the first floor of
of Premises:                  the Building and 7,482 Rentable Square Feet on
                              the second floor of the Building
<PAGE>

Commencement Date:            Seven weeks from securing the building permit
                              (anticipated to be week of December 11, 2000)

Term Expiration Date:         December 31, 2002

Rent Commencement Date:       To be determined as per Commencement Date above,
                              anticipated to be no later than January 19, 2001

Monthly Fixed Rent:           $43,151.31

Permitted Uses:               All permitted uses in the Headlease.

Parking Spaces:               Subject to prior written approval of Headlandlord
                              under the terms of the Headlease, Subtenant, at
                              subtenant's expense, may install several visitor
                              parking spaces in front of the entrance to the
                              Premises Subtenant shall be entitled to use an
                              additional 150 parking spaces.

Signs:                        Subject to prior written approval and signage
                              criteria of Headlandlord under the terms of the
                              Headlease, Subtenant, at Subtenant's expense, may
                              place signage at the entrance to the Premises.

     1.2  Exhibits.
          --------

     The exhibits listed below in this section are incorporated in this Sublease
by reference and are to be construed as part of this Sublease:

EXHIBIT A         Headlease
EXHIBIT B & C     Floor Plan of Premises

                                      -2-
<PAGE>

                                  ARTICLE II

                               PREMISES AND TERM

     2.1  Premises.  Subject to and with the benefit of the provisions of this
          --------
Sublease, Sublandlord hereby subleases the Premises to Subtenant, and Subtenant
subleases the Premises from Sublandlord.

     The Premises are subleased in their condition "as is" on the Commencement
Date.

     2.2  Term.  To have and to hold beginning on the Commencement Date and
          ----
continuing until the Term Expiration Date (the "Term"), subject to earlier
termination as provided herein.

     2.3  Early Access. Sublandlord shall allow Subtenant access to the Premises
          ------------
prior to the Commencement Date to install cabling, telephone systems, furniture
partitions and to perform other necessary tenant improvements.  Prior to
Subtenant's entry into the Premises as permitted hereunder, Subtenant shall
submit a schedule to Sublandlord (and Sublandlord's contractor, if so requested
by Sublandlord), for their reasonable approval, which schedule shall detail the
timing and purpose of Subtenant's entry.  Subtenant shall hold Sublandlord
harmless from and indemnify and protect and defend Sublandlord against any loss
or damage to the Premises or the Building and against injury to any person
caused by Subtenant's actions as a result of such entry, to the extent such loss
or damage is not covered by insurance carried or required to be carried under
this Sublease.

                                  ARTICLE III

                                     RENT

     3.1  Monthly Fixed Rent. Subtenant shall pay Sublandlord the Monthly Fixed
          ------------------
Rent in advance on the first calendar day of each month included, in the Term,
commencing on the Rent Commencement Date; and for any portion of a calendar
month at the beginning of or end of the term, the corresponding fraction of the
Monthly Fixed Rent in advance. Monthly Fixed Rent shall include HVAC, security
and nightly janitorial service five (5) days per week.

     3.2  Additional Rent. Pursuant to the Headlease, Sublandlord is required to
          ---------------
pay 100% of all operating, tax, maintenance and repair costs for the Building
(as such terms are defined in the Headlease), and such other amounts payable as
in the Headlease (collectively, the "Operating Costs").  Subtenant shall pay
Sublandlord as additional rent hereunder 32.14% of any increase over the base
year of all Operating Costs allocable to the periods of time included in the
Term (the "Additional Rent").  The base year for real estate taxes is July 1,
2000 through June 30, 2001 with real estate taxes in the amount of $65,000.  The
base year for all other operating costs is the 2000 operating budget with an
amount of $5.50 per Subtenant rentable square foot.  Subtenant shall pay such
amount within ten (10) days of billing by Sublandlord, which bills shall
include, where applicable, copies of the applicable statements from
Headlandlord.  Any surplus shall be promptly refunded to Subtenant and any
deficit in such payment shall be promptly paid by

                                      -3-
<PAGE>

Subtenant after the Headlandlord finally determines the amounts payable by the
Sublandlord under the Headlease.

     Capital repairs and replacements to the roof, structural elements and
Building systems shall be the sole responsibility of the Sublandlord and shall
not be included in the Operating Costs,

     3.3  Electricity. A separate meter for the measurement of electric
          -----------
consumption has been installed on the first floor of the Premises. Subtenant
shall pay as additional rent all amounts billed for the Premises by the
applicable utility company when due directly to the utility company. If such
electric charges are not payable directly to the utility company, Subtenant
shall pay such electric charges based on the separate meter to Sublandlord
within ten (10) days of Sublandlord's invoice on a monthly basis. Electric
consumption is not separately metered on the second floor of the Premises.
Subtenant shall pay as Additional Rent each month to Sublandlord with the
Monthly Fixed Rent a sum equal to $1.25 per rentable square foot (i.e. $779.38
per month) covering Subtenant's share of the cost of electricity for lights and
plugs consumed by Subtenant on the second floor of the Premises.

     3.4  Payment. All payments of Monthly Fixed Rent and Additional Rent shall
          -------
be made to Sublandlord at Sublandlord's Address set forth in Section 1.1 or to
such other address as Sublandlord may designate by notice to Subtenant from time
to time.

                                  ARTICLE IV

                             SUBTENANT'S COVENANTS

     Subtenant covenants during the Term and such further time as Subtenant
occupies any part of the Premises:

     4.1  Subtenant's Payments.  Subtenant shall pay all Monthly Fixed Rent,
          --------------------
Additional Rent and any other amounts payable when due.

     4.2  Maintenance and Repair. Subtenant shall, at its own cost and expense,
          ----------------------
keep and maintain all parts of the interior of the Premises in good condition in
accordance with the Headlease.

     4.3  Occupancy and Use. Subtenant shall not use the Premises for any uses
          -----------------
other than the Permitted Uses, and shall not make any use of the Premises which
is prohibited by any applicable law, ordinance, code, regulation, license,
permit, variances or governmental order.

     4.4  Alterations and Additions. Subtenant shall not make any improvements,
          -------------------------
repairs, alterations, replacements, decorations and/or additions to the Premises
without first obtaining the written approval of Sublandlord, which approval
shall not be unreasonably withheld or delayed, and the written approval of the
Headlandlord on the terms and conditions set forth in the Headlease.

                                      -4-
<PAGE>

     All construction work required or permitted by this Sublease shall be done
in a good and workmanlike manner and in compliance with all applicable laws and
all lawful ordinances, regulations and orders of governmental authority and
insurers of the building.

     4.5  Assignment and Subletting.  Except with Sublandlord's prior written
          -------------------------
consent, which consent shall not be unreasonably withheld or delayed, Subtenant
shall not assign, transfer, mortgage or pledge this Sublease, or sublease (which
term shall be deemed to include the granting of concessions and licenses and the
like) all or any part of the Premises, or suffer or permit this Sublease or the
leasehold estate hereby created or any other rights arising under this Sublease
to be assigned, transferred or encumbered, in whole or in part, whether
voluntarily, involuntarily or by operation of law, or permit the occupancy of
the Premises by anyone other than Subtenant.  Any attempted assignment,
transfer, mortgage, pledge, sublease or encumbrance without such consent shall
be void.

     In the event that any assignee or transferee of Subtenant pays to Subtenant
any amount in excess of the Monthly Fixed Rent, Additional Rent and any amounts
and/or charges then payable hereunder, Subtenant shall promptly pay one hundred
(100%) percent of said excess to Sublandlord as and when received by Subtenant.
If Subtenant shall receive from any assignee or transferee, either directly or
indirectly, any consideration for the assignment of this Sublease, either in the
form of cash, goods or services, Subtenant shall pay an amount equivalent to one
hundred (100%) percent of such consideration to Sublandlord as and when received
by Subtenant.

     Notwithstanding the foregoing, any assignment, transfer, mortgage or pledge
of this Sublease is subject to and conditioned upon receipt of the prior written
consent of the Headlandlord as provided in the Headlease.

     No assignment or subletting shall affect the continuing primary liability
of Subtenant (which, following assignment, shall be joint and several with the
assignee).

     4.6  Indemnification. Except to the extent caused by the gross negligence
          ---------------
or willful misconduct of Landlord, its agents, servants or employees, Subtenant
shall indemnify and hold harmless Sublandlord, Sublandlord's agents and
employees from and against any and all claims, demands, suits, judgments,
liabilities, costs and expenses, including reasonable attorneys' fees and
damages, both real and alleged, arising out of or in connection with Subtenant's
use and possession of the Premises, or arising out of the failure of Subtenant,
its agents, contractors or employees to perform any covenant, term or condition
of this Sublease or of the Headlease to be performed by Subtenant hereunder, or
any injury to person or damage to property on or about the Premises, resulting
in part of whole by the negligence or misconduct of Subtenant, its agents,
servants or employees. Sublandlord agrees to indemnify and hold Subtenant
harmless from and against any and all claims, demands, suits, judgments,
liabilities, costs and expenses, including reasonable attorneys' fees, rising
out of the failure of Sublandlord, its agents, contractors or employees to
perform any covenant, term or condition of this Sublease or of the Headlease to
be performed by Sublandlord hereunder.

     4.7  Insurance.  Subtenant shall maintain in responsible companies with a
          ---------
general policy rating of A or better and a financial class of VI or better by
A.M.  Best, Inc. and qualified

                                      -5-
<PAGE>

to do business and in good standing in Massachusetts, comprehensive general
liability insurance covering the premises insuring Sublandlord and Headlandlord
as well as Subtenant with limits which shall, at the commencement of the Term,
be at least $2,000,000 per occurrence in respect of injury to person (including
death) and from time to time during the Term shall be for such higher limits, if
any, as are customarily carried in the Marlborough and Westborough areas with
respect to similar properties, property damage insurance which shall at the
commencement of the Term be at least $500,000 per occurrence in respect of
property damage or destruction, including loss or use thereof and worker's
compensation insurance with statutory limits covering all of Subtenant's
employees working in the Premises. In addition, Subtenant shall be responsible
for insuring its personal property. Prior to the Commencement Date, Subtenant
shall deposit promptly with Sublandlord certificates for such insurance naming
Sublandlord and Headlandlord as additional insureds, and all renewals thereof
not less than fifteen (15) days prior to expiration bearing the endorsement that
the policies will not be canceled or changed to reduce insurance provided
thereby until after 30 days' written notice to Sublandlord.

                                   ARTICLE V

                              CASUALTY AND TAKING

     5.1  Termination of Headlease. In the event that during the Term, all or
          ------------------------
any part of the Premises or the Headleased Premises are destroyed or damaged by
fire or other casualty or taken by eminent domain, and either Sublandlord or
Headlandlord terminates the Headlease pursuant to its terms because of such
damage, destruction or taking, then this Sublease shall likewise terminate on
the same date that the Headlease terminates. Sublandlord shall give Subtenant
prompt notice of such termination and the date on which it shall occur.

     5.2  Repair and Restoration. In the event any such damage, destruction or
          ----------------------
taking of the Premises occurs and this Sublease is not terminated pursuant to
Section 5.1, above, then Sublandlord shall use reasonable efforts to cause
Headlandlord to repair and restore the Premises to the extent required by the
terms of the Headlease.

     5.3  Reservation of Award.  Any and all rights to receive awards made for
          --------------------
damages to the Premises and the leasehold hereby created accruing by reason of
exercise of eminent domain or by reason of anything lawfully done in pursuance
of public or other authority, are reserved to Sublandlord and Headlandlord.
Subtenant hereby releases and assigns to Sublandlord and Headlandlord all
Subtenant's rights to such award and covenants to deliver such further
assignments, and assurances thereof as Sublandlord or Headlandlord may from time
to time request.

                                  ARTICLE VI

                                   HEADLEASE

     6.1  Sublease Subject to Headlease. This Sublease is subject to the
          -----------------------------
Headlease. Subject to this Section 6.1, all terms and conditions of the
Headlease are incorporated into and made a part of this Sublease as if
Sublandlord were the landlord thereunder and Subtenant were the tenant. In case
of conflict between the incorporated provisions of the Headlease and the

                                      -6-
<PAGE>

remaining provisions of this Sublease, the latter shall control. Subtenant
assumes and agrees to perform the tenant's obligations under the Headlease
during the Term, except that the obligation to pay rent or other amounts to
Headlandlord under the Headlease shall not be an obligation of Subtenant, and
Subtenant shall instead pay the rent to Sublandlord under this Sublease.
Subtenant shall not commit or suffer any act or omission that will violate any
of the provisions of the Headlease.

     If the Headlease terminates as a result of a default or breach of Subtenant
under this Sublease and/or the Headlease, then the Subtenant shall be liable to
the Sublandlord for the direct damage suffered as a result of such termination.
Subtenant covenants not to commit or suffer any act or omission that will
violate the Headlease.

     6.2  Excluded Obligations. Notwithstanding anything to the contrary herein,
          --------------------
the incorporated provisions of the Headlease are amended or qualified as
follows:

          i.   Sublandlord shall not be liable under any circumstances for a
loss of or injury to property, or interference with Subtenant's business,
however occurring, incidental to any failure to furnish any utilities or
services.

          ii.  Sublandlord shall have no responsibility to perform or construct
(or to pay the cost of performing or constructing) any repair, maintenance or
improvement in or to the Premises, except as specifically set forth in Section
2.1 of this Sublease.

          iii.  Rent shall be abated under this Sublease only to the extent that
Sublandlord receives a corresponding rent abatement under the Headlease.

          iv.   Wherever the Headlease grants to Sublandlord a grace or cure
period, the corresponding grace or cure period under this Sublease shall be two
(2) business days shorter in duration.

     The parties acknowledge that Sublandlord's ability to satisfy certain of
its obligations to Subtenant under this Sublease is contingent upon the full and
timely performance of Headlandlord's obligations under the Headlease.  The
parties further acknowledge that, while Sublandlord will use reasonable efforts
to cause Headlandlord to perform its obligations under the Headlease,
Sublandlord will not be liable to Subtenant for any breach of Sublandlord's
obligations under this Sublease, nor shall such breach diminish Sublandlord's
rights hereunder, where the same is caused by or attributable to the failure of
Headlandlord to perform its obligations under the Headlease.

     6.3  Headlandlord's Rights. Headlandlord shall have all rights with respect
          ---------------------
to the Premises which it has reserved to itself as landlord under the Headlease.

     6.4  Termination of Headlease. In the event that Headlandlord terminates
          ------------------------
the Headlease pursuant to its terms or the Headlease otherwise terminates or
expires, this Sublease shall likewise and simultaneously terminate.

                                      -7-
<PAGE>

                                  ARTICLE VII

                                 MISCELLANEOUS

     7.1  Notices from One Party to The Other. All notices required or permitted
          -----------------------------------
hereunder shall be in writing, duly signed by the party giving such notice and
transmitted by prepaid registered or certified mail, return receipt requested,
by telegram or telefax, or delivered by hand, and addressed as follows:

to Sublandlord:                           ePresence, Inc.
                                          120 Flanders Road
                                          Westborough, MA
                                          Fax No.  (508) 366-6846
                                          Attn: Legal Department

with a copy to:                           Hale and Dorr LLP
                                          60 State Street
                                          Boston, MA 02110
                                          Fax No.  (617) 526-5000
                                          Attn: Delta I.  Breton, Esq.

to Subtenant:                             Switchboard Incorporated
                                          _____________________________
                                          _____________________________
                                          Fax No. _____________________
                                          Attn: _______________________

with a copy to:                           _____________________________
                                          _____________________________
                                          _____________________________
                                          Switchboard Legal Department
                                          _____________________________

or to such other address as Sublandlord or Subtenant shall designate by written
notice to each other.  Any notice shall be deemed duly given on the second
business day following the date of mailing, or when delivered to such address by
hand, or if transmitted by telefax or telegram, on the business day received.

     7.2  Estoppel Certificate. Upon not less than twenty (20) days prior notice
          --------------------
by the Sublandlord, Subtenant shall execute, acknowledge and deliver to
Sublandlord a statement in writing, addressed to such person as Sublandlord
shall designate, certifying (a) that this Sublease is unmodified and in full
force and effect, (b) the dates to which Monthly Fixed Rent, Additional Rent
have been paid, and (c) that Sublandlord is not in default hereunder (or, if in
default, specifying the nature of such default in reasonable detail). Any such
certificate may be relied upon by the person to which it is addressed as to the
facts stated therein.

                                      -8-
<PAGE>

     7.3  Brokerage. Subtenant and Sublandlord mutually represent and warrant
          ---------
that they have dealt with no broker in connection with this transaction except
for CRESA Partners (the "Broker"). Each agrees to defend, indemnify and save the
other harmless from and against any and all cost, expense or liability for any
compensation, commissions or charges claimed by any broker or agent other than
the Broker, with respect to the indemnifying party's dealings in connection with
this Sublease. Sublandlord shall pay the commission due to the Broker,

     7.4  Applicable Law.  This Sublease shall be governed by and construed in
          --------------
accordance with the laws of the Commonwealth of Massachusetts.

     7.5  Security Deposit. Upon execution of this Sublease, Subtenant shall
          ----------------
deliver to Sublandlord the Security Deposit, such sum to be held by Sublandlord
as security for the performance of Subtenant's obligations under this Sublease.
The Security Deposit shall be held by Sublandlord without interest and
Sublandlord shall be entitled to commingle the Security Deposit with its other
funds,

     7.6  Construction.  If any term, covenant, condition or provision of this
          ------------
Sublease or the application thereof to any person or circumstances shall be
declared invalid or unenforccable by the final ruling of a court of competent
jurisdiction having final review, the remaining terms, covenants, conditions and
provisions of this Sublease and their application to persons or circumstances
shall not be affected thereby and shall continue to be enforced and recognized
as valid agreements of the parties.

     This Sublease constitutes the entire agreement between the parties hereto
with respect to the transactions contemplated herein, and it supersedes all
prior discussions, understandings or agreements, including without limitation
the Offer To Sublease, between the parties.

     There are no oral or written agreements between Sublandlord and Subtenant
affecting this Sublease.  This Sublease may be amended, and the provisions
hereof may be waived or modified, only by instruments in writing executed by
Sublandlord and Subtenant.

     The titles of the several Articles and Sections contained herein are for
convenience only and shall not be considered in construing this Sublease.

     Unless repugnant to the context, the words "Sublandlord" and "Subtenant"
appearing in this Sublease shall be construed to mean those named above and
their respective heirs, executors, administrators, successors and assigns, and
those claiming through or under them respectively.  If there be more than one
tenant, the obligations imposed by this Sublease upon Subtenant shall be joint
and several.

     7.7  Access and Security. Normal Building hours shall be from 7:00 a.m. to
          -------------------
6:00 p.m. Monday through Friday. The Building has a twenty-four (24) hour card
access system. Subtenant shall be responsible for its own security card access
at the entrance to the Premises.

     7.8  Signs.  Subject to the prior written approval and signage criteria of
          -----
Headlandlord under the terms of the Headlease, Subtenant, at Subtenant's
expense, may place signage at the side entrance to the Premises.  Sublandlord
shall promptly arrange and pay for the insertion of Subtenant's name and suite
number into the building directory.

                                      -9-
<PAGE>

     7.9  Cafeteria.  Subtenant shall have the right to use the cafeteria in the
          ---------
Building during the Term of this Sublease under the terms of a cost sharing
arrangement separate from this agreement.

     7.10 Consent of Headlandlord.  Subtenant acknowledges that this Sublease is
          -----------------------
subject to the consent of the Headlandlord.  Within three (3) business days
after the execution of this Sublease, Sublandlord shall notify and forward an
originally executed copy of this Sublease to the Headlandlord and shall request
Headlandlord's consent thereto.  Upon receiving Headlandlord's response,
Sublandlord shall notify Subtenant as to whether or not the Headlandlord
consented to the sublease.  In the event the Headlandlord does not consent to
the sublease, this Sublease shall terminate and be of no further force or
effect.

     THIS SUBLEASE is executed as a sealed instrument in two or more
counterparts on the day and year first above written.

SUBLANDLORD:

EPRESENCE, INC.

By: /s/ John F. Mitchell
    -------------------------------
     Name:  John F. Mitchell
     Title: Director of Finance

SUBTENANT:

SWITCHBOARD INCORPORATED-

By: /s/ John Jewett
    -------------------------------
     Name:  John Jewett
     Title: Vice President and CEO

                                      -10-

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