Exhibit 10.10

The omitted  portions  indicated by brackets have been separately filed with the
Securities  and  Exchange  Commission  pursuant  to a request  for  confidential
treatment under Rule 24b-2 of the Securities Exchange Act of 1934, as amended.

                                                  Dated as of September 17, 1996

SAMSUNG ELECTRONICS CO., LTD.
9th Floor, Joong-ang Daily News Building
7, Soonhwa-dong, Choong-Ku
C.P.O. Box 2775
Seoul
KOREA
Attention:        Mr. S. N. Lee
                  General Manager of International
                     Wireless Products Group
and

SAMSUNG ELECTRONICS CO., LTD./
SAMSUNG TELECOMMUNICATIONS AMERICA, INC.
1501 LBJ Freeway, Suite 410
Dallas, Texas  75234
Attention:        Mr. H. J. Lee
                  Director of Strategic Business
                     Development Team

Gentlemen:

     Reference is made to the Purchase and Supply  Agreement  (the  "Agreement")
dated as of the date hereof  among  Samsung  Electronics  Co.,  Ltd.,  a company
organized  under  the laws of The  Republic  of Korea,  as  Vendor,  and  Sprint
Spectrum  L.P., a Delaware  limited  partnership,  as Owner.  Terms used but not
defined herein shall have the meanings set forth in the Agreement.

     In connection with and as consideration for the execution of the Agreement,
the Parties agree as follows:

     1. Marketing  Fund.  Throughout the Term the Vendor will (without any other
precedent or subsequent requirement other than as specifically set forth in this
Paragraph 1) contribute cash amounts equal to [____________] of the invoiced FOB
Point price of any Subscriber Units (and any accompanying  Material Accessories)
so invoiced by the Vendor to the Owner for such Products  purchased and paid for
by the Owner  pursuant to the terms of the Agreement to a separate fund owned by
the Owner and designated in writing to the Vendor from time to time by the Owner
(the "Marketing Fund"). Any and all amounts in the Marketing Fund may be used by
the Owner in its sole and absolute discretion for any purpose in connection with
the  marketing or promotion  by way of print  media,  broadcasting  media and/or
outdoor advertising of the Nationwide Network or any part thereof which includes
the use of the Vendor's branding, subject to the terms of Subsection 3.17(b) and
Section 8 of the Agreement.  On a quarterly  basis, the Owner will submit to the
Vendor a report  on the  ongoing  use of the  funds in the  Marketing  Fund.  In
accordance  with the terms of this  letter  agreement,  the Vendor must make any
such  contribution  to the Marketing  Fund within thirty (30) days of receipt by
the Vendor of full  payment by the Owner of amounts  due under any such  invoice
for Subscriber Units (and any accompanying Material Accessories) pursuant to the
terms  of the  Agreement.  To the  extent  the  Vendor  fails  to make  any such
contribution  to the Marketing Fund pursuant to and in accordance with the terms
hereof,  the Owner  will  have the right to  withhold  any such  amounts  not so
contributed by the Vendor in contravention of the terms hereof or the Agreement,
from future invoices for Products  ordered by the Owner pursuant to the terms of
the Agreement.

     2. Launch Fee. Within thirty (30) days of the Commencement Date, the Vendor
will  pay  by  wire   transfer   into  an  account   designated  by  the  Owner,
[_______________________]  as payment to the Owner of the  marketing  launch fee
(the "First  Generation  Launch Fee") as further  consideration  for the Owner's
marketing and  promotion  pursuant to the terms of the  Agreement.  Within sixty
(60) days of the first  availability of Second  Generation  Subscriber  Units in
accordance with the terms of the Agreement, the Vendor will pay by wire transfer
into an account designated by the Owner,  [______________________] as payment to
the Owner of the second  generation  launch fee (the "Second  Generation  Launch
Fee" and together with the First  Generation  Launch Fee, the "Launch  Fees") as
further  consideration for the Owner's  marketing and promotion  pursuant to the
terms of the Agreement. The proceeds of the Launch Fees may be used by the Owner
in its sole discretion for the marketing of and/or  publicity for the Nationwide
Network,  or any part  thereof.  Other  than as  specifically  set forth in this
Paragraph  2, the  Vendor's  obligation  to pay the Launch Fees on the terms set
forth  in  this  Paragraph  2 is  without  any  other  precedent  or  subsequent
requirement.  Until and unless the Launch Fees are paid hereunder, the Owner (at
such time) will have the right,  but not the  obligation,  to suspend all or any
part of its performance under the Agreement.

     3. The Vendor will work with the Owner to coordinate the Vendor's marketing
and  promotional  efforts in the United  States  with the  Owner's  city-by-city
launch of PCS commercial service.

     4.  Throughout  the Term,  the Owner  will  provide  the  Vendor  quarterly
marketing strategy and expenditures  reports which will describe the Owner's use
of the Launch Fees and the Marketing Fund monies.

     The terms and provisions of this letter  agreement shall be governed by all
of the terms of the  Agreement,  to the extent  applicable  (including,  but not
limited  to,  Sections 5, 8, 9, 10 and 11) and shall be deemed by the Vendor and
the Owner to be a material  part of and material to the  Agreement.  This letter
agreement shall be governed by and construed in accordance with New York law.

     This letter  agreement may be executed in any number of  counterparts,  and
each such counterpart shall be deemed to be an original instrument, but all such
counterparts together shall constitute one agreement.

     Please  indicate your agreement with the foregoing by executing this letter
where indicated below.
                                      Sincerely,

                                      SPRINT SPECTRUM L.P.

                                      By:  /s/ Bernard A. Bianchino
                                      Name:  Bernard A. Bianchino
                                      Title:  Chief Business Development Officer

AGREED TO BY:

SAMSUNG ELECTRONICS CO., LTD.

By:  /s/ Y.R. Song
Name:  Y. R. Song
Title:  Vice President