Exhibit 10.16


                                   CAIS, INC.
                             1232 22nd Street, N.W.
                            Washington, D.C.  20037
                              Tel. (202) 463-8500
                               Fax (202) 463-7190
                                        

                                         August 1, 1997

Mr. David D. Goodman
Inline Connection Corporation
730 N. Danville Street
Arlington, VA  22201
 
Dear David:

This will confirm our agreement regarding certain modifications to the November
5, 1996 Agreement for Cooperative Use of Communication Patents among Inline
Connection Corporation, you in your individual capacity, and CAIS, Inc. (the
"Agreement").

For good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, the Agreement is hereby amended and modified as follows:

1.   Section 12 of the Agreement currently provides in pertinent part that
"Should CAIS find patent protection desirable on new developments by David D.
Goodman or other Inline personnel covered by this Agreement, Inline shall file
appropriate patent application and will prosecute such application at Inline's
expense." Inline has requested, and CAIS has agreed, that because of the recent
increase in patent related expenses and the expectation that such increased
expenses will continue in the near term, that this arrangement be modified as
follows:

     a.  Upon request by Inline, CAIS shall advance funds to Inline for the
purpose of Inline's payment of expenses related to patent applications and
prosecutions contemplated by the provisions of Section 12 of the Agreement (the
"Patent Expenses") provided that:

          (i)  Inline has received CAIS's approval and consent prior to
     authorizing and incurring such Patent Expenses; and

          (ii)   Inline has complied with its obligation under Section 12 of the
     Agreement to consult with attorneys for CAIS regarding the scope and
     sufficiency of patent protection for the TWP technology covered by the
     Agreement.

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     b.  Such advances by CAIS shall accrue interest at a rate of 8% per annum
from the date they are advanced to Inline until repaid.  If  not repaid by
Inline sooner, such advances, including accrued interest,  shall be recoverable
by CAIS from Inline as a partial offset against royalty payments otherwise due
from CAIS to Inline pursuant to Sections 7 and/or 8 of the Agreement.  For
purposes of this provision, partial offset shall mean that CAIS shall be
entitled to hold back and apply to such recovery fifty percent (50%) of the
royalties otherwise due from CAIS to Inline.

     c.  If and to the extent the Agreement is terminated for any reason prior
to the full offset of such advances and accrued interest by royalties otherwise
becoming due from CAIS to Inline, then the balance, if any, of such advances
including accrued interest, shall be due and payable from Inline to CAIS not
later than 90 days from the effective date of such termination.

2.  During the term of the Agreement, and for a period of one year thereafter,
neither Inline nor CAIS shall attempt to hire away the other's employees or
provide the other's employees with any form of compensation or inducement  that
was not approved in advance by the employing entity.


All other terms and conditions of the Agreement remain in full force and effect.

If the above reflects your understanding and meets with your approval, please so
indicate by countersigning below on behalf, respectively, of Inline and in your
individual capacity.
Sincerely,

CAIS, Inc.

By: /s/ Ulysses G. Auger, II 
    -----------------------------------           
      Ulysses G. Auger, II, President


                          Agreed to:

                          Inline Connection Corporation

                          By: /s/ David D. Goodman
                              --------------------------------
                              David D. Goodman, President

                                   8/11/97
                          ---------------------
                          Date


                          Agreed to:

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                          /s/ David D. Goodman
                          --------------------------------
                          David D. Goodman, in his individual capacity

                                   8/11/97
                          ------------------------
                          Date

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