<PAGE>

                      SECURITIES AND EXCHANGE COMMISSION
                             Washington, DC 20549

                                  FORM 10-Q/A

                                Amendment No. 1

(Mark One)
[X]  QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934

                                      OR

[_]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934


FOR THE QUARTER ENDED JUNE 30, 1998             COMMISSION FILE NUMBER:  0-27442



                             OMNIPOINT CORPORATION
                    THREE BETHESDA METRO CENTER, SUITE 400
                              BETHESDA, MD 20814

                                (301) 951-2500

          DELAWARE                                               04-2969720
          --------                                               ----------
(State or other jurisdiction of                               (I.R.S. employer
incorporation or organization)                               identification No.)


          SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:



                                                   NAME OF EACH EXCHANGE
     TITLE OF EACH CLASS:                           ON WHICH REGISTERED:
     --------------------                           --------------------
   COMMON STOCK, PAR VALUE                         NASDAQ NATIONAL MARKET
       $0.01 PER SHARE


         SECURITIES REGISTERED PURSUANT TO SECTION 12 (g) OF THE ACT:

                                     NONE

  Indicate by check mark whether the Registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
Registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days.  Yes [X]  No __

  Shares of common stock outstanding as of August 10, 1998 were 52,748,615.

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                                  Form 10-Q/A

                                Amendment No. 1


                    Omnipoint Corporation and Subsidiaries


                               Table of Contents

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      Part II.  OTHER INFORMATION AND SIGNATURE                                             3
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                          Part II -- Other Information

ITEM 5: OTHER INFORMATION

        None

ITEM 6: EXHIBITS AND REPORTS ON FORM 10-Q

(a)  Exhibits

       10.63   Loan agreement, dated June 25, 1998, by and between Omnipoint MB
               Holdings, L.L.C. and Bank of America National Trust and Savings
               Association.

       10.64   Amended and restated loan agreement, dated June 25, 1998, by and
               between Omnipoint MB Holdings, L.L.C. and Ericsson Inc.

       27.1    Financial Data Schedule

(b)  REPORTS ON FORM 8-K

        None.



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                                   SIGNATURE
                                   ---------

Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned thereunto duly authorized.

                                      OMNIPOINT CORPORATION

Date: January 20, 2000                /s/ Harry Plonskier
                                      ------------------------------
                                      Harry Plonskier
                                      Acting Chief Financial Officer