<PAGE>   1
  Confidential  Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


                                                                   EXHIBIT 10.27


                                  AMENDMENT ONE
                                       TO
                     RICOCHET(TM) CHANNEL PARTNER AGREEMENT
                                       FOR
                          AUTHORIZED SERVICE PROVIDERS
                                 BY AND BETWEEN
             METRICOM, INC. AND GOAMERICA COMMUNICATIONS CORPORATION
                             DATED SEPTEMBER 1, 2000

Reference is made to that certain Ricochet(TM) Channel Partner Agreement for
Authorized Service Providers effective September 1, 2000 (the "Agreement")
between METRICOM, INC. ("Metricom"), a Delaware corporation, with it principal
offices at 333 West Julian Street, San Jose, CA 95110, and GOAMERICA
COMMUNICATIONS CORPORATION ("ASP") located at 401 Hackensack Avenue, New Jersey,
07601.

1.   The Agreement is amended by adding the following as a new Section:

     ASP  CO-OPERATIVE MARKETING FUNDING PROGRAM.

     Metricom will establish a program (the "Co-op Program") under which
     Metricom will make funds available to ASP, and which ASP shall earn under
     the requirements established in this Section ("Co-Op Funds"), to assist ASP
     in its efforts to effectively endorse, promote and sell the Service as
     contemplated in this Agreement for the year 2000. The Co-op Program is
     limited to the acquisition of new Ricochet(TM) subscribers (excludes
     existing subscribers of the [**] Ricochet(TM) service) and does not apply
     to any customer loyalty, retention or other programs directed at existing
     Subscribers. To be eligible under the Co-op Program, all programs require
     Metricom's written approval prior to the release of any such program.

     1. PROGRAM DESCRIPTION. The Co-op Program is comprised of three categories:

     (A) CO-OPERATIVE ADVERTISING/DIRECT MAIL. This category covers lead
generation, advertising, media placement and non-installed-base direct mail
programs. Metricom will make available, to ASP, a mix of broadcast (television
and radio), print and online in each GSA at a discount of [**] percent ([**]%)
off of the production cost. The discounted rate, as reflected in Table 1.A, will
be deducted directly from ASP's earned Ad Funds, subject to the limitations set
forth in Paragraph 2(b) of this Section.

     TABLE 1.A CREATIVE RATES

<TABLE>
<CAPTION>
                                                                              PRODUCTION
                     MEDIA                                    VALUE              COST          ASP RATE
                     -----                                    -----           ----------       --------
<S>                                                           <C>             <C>              <C>
TV* - (:30 spot) :20 second Ricochet with :10 partner
taggable (partner can choose among 4 spots)                    $[**]            $[**]            $[**]
Radio - (:30 spot) :20 second Ricochet with :10 partner
taggable                                                       $[**]            $[**]            $[**]
Newspaper, Black and White (4x10, Jr. page, full page)         $[**]K           $[**]            $[**]
Magazine/Trade Publication                                     $[**]            $[**]            $[**]
Online                                                         $[**]            $[**]K           $[**]
Direct Mail (four color post card)                             $[**]            $[**]K           $[**]
</TABLE>

<TABLE>
<S>                                <C>                                                          <C>
Rev. 082100eap                     Amendment One to Ricochet(TM)Channel Partner Agreement       Page 1 of 4
                                   for Authorized Service Providers Metricom Confidential
                                   and Proprietary Not for Use or Disclosure Outside of
Metricom Initials:                 Metricom or ASP Except Upon Written Approval                 GoAmerica Initials:
                  --------------                                                                                   ------------
</TABLE>
<PAGE>   2
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


     In the event ASP elects to develop its own campaign, using Metricom's
co-branded mark, Metricom shall have the right to review and approve, in
writing, such campaign prior to production. ASP agrees not to launch any
campaign earlier than [**] from Metricom's Ricochet(TM) brand campaign launch as
determined by Metricom and communicated in writing to ASP by an authorized
representative of Metricom.

          (I) DIRECT MAIL. ASP has the option to use Metricom provided Creative
     or develop its own creative. In either event, Metricom shall have the right
     to review and approve, in writing, all creative prior to production.

          (B) MARKET DEVELOPMENT. This category is designed to offset the costs
     of special programs and non-traditional advertising, subject to prior
     written approval by Metricom. Such programs include, but are not limited
     to:

               Ricochet Demo Program

               Event sponsorships (ASP sales force kick-off or
               jointly sponsored industry events)

               Joint PR Efforts

               Video News Releases/Promotional Videos

               Collateral Development

               Referral Programs

               In-box or other special promotions

               Coffee Sleeves/Bar Coasters Web Marketing Sales Force
               Incentives (trips, bonuses, etc.)

          (C) JUMP-START. This category allows ASP to use Incentive Funds for
     installed-based marketing programs ("Jump Starts") during the initial [**]
     offering the Service in any GSA. Upon written approval by Metricom of ASP's
     program, Metricom will credit ASP's Marketing Account with the Incentive
     Funds. Jump Starts can include, but are not limited to, email, direct mail,
     web-based, refer a friend and modem rebate programs.

          2. FUNDS. Metricom will make available fifty dollars ($[**]) for
     advertising and direct mail programs ("Ad Funds") plus [**] dollars ($[**])
     for market development programs ("MD Funds") for a total one-time amount of
     [**] dollars ($[**]) per new subscriber (excludes existing subscribers of
     the [**]Ricochet(TM) service) that ASP registers, with additional
     incentives available up to a maximum of [**] dollars ($[**]) ("Incentive
     Funds") for the year 2000. Ad Funds, MD Funds and Incentive Funds shall be
     referred to collectively as Co-op Funds. Co-op Funds are available
     exclusively to the ASP, however, ASP may elect to share its Co-op Funds
     with its Reseller(s) provided requests for reimbursement and the
     disbursement of such is handled by ASP.

          (A) MARKETING ACCOUNT. Upon execution of this Amendment One, Metricom
     will pre-build ASP's co-operative marketing account ("Marketing Account")
     based on ASP's Guaranteed ASP subscribers for the first [**]. Metricom will
     reconcile the difference between the actual number of ASP Subscribers and
     the Guaranteed ASP Subscribers at the start of the [**] and make any
     adjustments necessary. The account will be calculated on a [**] basis,
     using the information contained in the reports described in Section 5.2 of
     the Agreement. The account details will be provided to ASP on a monthly
     basis.

          (B) REIMBURSEMENT. Reimbursement will be at [**] percent of ([**]%) of
     pre-approved programs limited to the applicable earned Co-op Funds
     available in ASP's Marketing Account as of the date of the invoice
     submitted for reimbursement. All requests for reimbursement ("Claim") must
     be received by Metricom within [**] days after the ending run date of the
     program or [**], whichever occurs first.

<TABLE>
<S>                                <C>                                                          <C>
Rev. 082100eap                     Amendment One to Ricochet(TM)Channel Partner Agreement       Page 2 of 4
                                   for Authorized Service Providers Metricom Confidential
                                   and Proprietary Not for Use or Disclosure Outside of
Metricom Initials:                 Metricom or ASP Except Upon Written Approval                 GoAmerica Initials:
                  --------------                                                                                   ------------
</TABLE>

<PAGE>   3
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.


     (C) INSUFFICIENT FUNDS. In the event ASP does not have sufficient funds in
the applicable fund category to cover the Claim, ASP may determine how much, if
any, of the available funds should be applied toward the Claim. ASP shall
indicate such rate on the applicable claim form.

     (D) CAP ON FUNDS. ASP's year 2000 Co-op Funds are capped at [**] dollars
($[**]). In the event ASP reaches this cap early in the Co-op Program and has
demonstrated successful programs, the parties agree to negotiate a new cap on
good faith.

     (E) EXPIRATION OF FUNDS. Co-op Funds accrued in the year 2000, must be
designated for a program by [**]. Such programs must be completed and funds
claimed by [**]. Complete proof of performance documents must be submitted by
[**]. ASP'S Marketing Account will be debited any unsubstantiated amounts. Any
unused funds shall be forfeit.


     3.   REQUIREMENTS OF ELIGIBILITY/LOSS OF ELIGIBILITY.

          (A)  ELIGIBILITY. In order to be eligible for Co-op Funds, ASP must
               meet the following requirements:

              (I) Adherence to the requirements set forth in this Amendment One;
              (II) Compliance with Metricom corporate graphics standards on logo
          usage, advertising guidelines and creative guidelines;
              (III) Written pre-authorization from Metricom Corporate Marketing
          for all campaigns and/or programs related to the Service;
              (IV) Submission of appropriate forms along with supporting
          documents as set forth in the Pre-Approval Process below;
              (V) Submission of appropriate proof of performance (creative, tear
          sheets, scripts, media schedule, etc.) and copies of invoices; and
              (VI) A Marketing account in good standing.

          (B)  LOSS OF ELIGIBILITY.

              (I) Metricom reserves the right to re-evaluate ASP's participation
          in the Co-op Program if ASP experiences an unusually high churn rate
          ([**] percent ([**]%) or higher). Such re-evaluation may result in
          freezing ASP's Market Account or termination of ASP's participation in
          the Co-op Program.

              (II) In the event of termination of the Agreement or this
          Amendment for any reason, including without limitation, failure to
          renew, ASP misrepresentation of Metricom or abuse of the Co-op
          Program, ASP's participation in the Co-op Program shall be terminated
          immediately and ASP shall have [**] thereafter in which to submit all
          claims for reimbursements which were submitted and approved for
          reimbursement prior to termination of the Agreement or this Amendment
          One. Any unused Co-op Funds will be forfeit.

     4.   PROGRAM PRE-APPROVAL PROCESS. ASP may commence submitting pre-approval
forms, samples of which are attached hereto as exhibits, once ASP has
accumulated sufficient Co-op Funds to cover the program for which ASP is
requesting reimbursement.

          1.   Fill out the appropriate pre-approval form (i.e., Co-op
               Advertising/Direct Mail, Marketing Development, or Jump-Start).
          2.   Submit the completed pre-approval form to the address set forth
               in Paragraph 6.
          3.   If approved, Metricom will return the reimbursement request form
               signed by an authorized representative of Metricom within [**]
               working days from receipt of request by Metricom. If the
               request is not approved, Metricom will return the form with
               recommended changes. ASP may resubmit the form after the
               recommended changes have been made.
<TABLE>
<S>                                <C>                                                          <C>
Rev. 082100eap                     Amendment One to Ricochet(TM)Channel Partner Agreement       Page 3 of 4
                                   for Authorized Service Providers Metricom Confidential
                                   and Proprietary Not for Use or Disclosure Outside of
Metricom Initials:                 Metricom or ASP Except Upon Written Approval                 GoAmerica Initials:
                  --------------                                                                                   ------------
</TABLE>



<PAGE>   4
  Confidential Materials omitted and filed separately with the Securities and
                Exchange Commission. Asterisks denote omissions.

     5.   CLAIM PROCEDURE. Metricom will process Claims as expeditiously as
possible. If the Claim is approved, ASP's Marketing Accounting will be debited
and a check for expenditures other than those purchased from Metricom, will be
mailed to ASP within four weeks after approval. Please allow three (3) weeks for
processing. A sample of the claim is attached hereto as an exhibit.

          1.   Submit a completed claim form with the applicable proof of
               performance (creative, tear sheet, scripts, media schedule,
               photographs, etc.), a program/campaign evaluation report and the
               applicable invoices to the address identified in Paragraph 6.

          2.   Reimbursement requests must be received by Metricom Corporate
               Department within [**] after the ending run date of a program or
               [**] whichever comes first.

     6.   FORM SUBMITTAL. Please submit completed Pre-Approval Forms and Claim
Forms, along with required attachments to:

                        Corporate Marketing
                        Attn:  Luz A. Berg
                        Metricom, Inc.
                        333 West Julian Street
                        San Jose, CA  95110
                        Phone:  408-282-4189
                        Fax:    408-282-3028
                        Email:  iberg@metricom.com


     7.   ADDITIONAL TERMS.

          (A)  The Co-op Program will be reviewed annually.

          (B)  Metricom reserves the right to modify or terminate the Co-op
               Program at any time.

          (C)  All material shall comply with all federal, state and local laws.
     Metricom disclaims all liability or responsibility for an advertising or
     promotion by ASP.

To the extent that this Amendment is inconsistent with the Agreement, this
Amendment shall govern and shall be deemed to amend and supersede the Agreement
as of the date hereof. All terms used herein and not otherwise defined shall
have the same meanings ascribed to them in the Agreement. Except as expressly
set forth herein, the Agreement remains in full force and effect.

IN WITNESS WHEREOF, the parties hereto have caused this amendment to be executed
by their duly authorized representatives effective on the 1st day of September,
2000.

<TABLE>
<CAPTION>
<S>                                                  <C>
METRICOM, INC.                                       GOAMERICA COMMUNICATIONS CORPORATION:

By:    /s/ John G. Wernke                            By:    /s/ Francis J. Elenio

Name:  John G. Wernke                                Name:  Francis J. Elenio

Title: Sr. V.P. Marketing and Sales                  Title: CFO

Date:  8/31/00                                       Date:  8/31/00
</TABLE>

<TABLE>
<S>                                <C>                                                          <C>
Rev. 082100eap                     Amendment One to Ricochet(TM)Channel Partner Agreement       Page 4 of 4
                                   for Authorized Service Providers Metricom Confidential
                                   and Proprietary Not for Use or Disclosure Outside of
Metricom Initials:                 Metricom or ASP Except Upon Written Approval                 GoAmerica Initials:
                  --------------                                                                                   ------------
</TABLE>