March 6, 1998 PriCellular Corporation 711 Westchester Avenue White Plains, NY 10604 Dear Sirs: This will confirm that we hereby agree to be bound by Section 4.05 of the Voting Agreement dated as of the date hereof by and among American Cellular...

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                                                                       Exhibit 6



                                                                   March 6, 1998

PriCellular Corporation
000 Xxxxxxxxxxx Xxxxxx
Xxxxx Xxxxxx, XX 00000


Dear Sirs:

     This will confirm that we hereby agree to be bound by Section 4.05 of the
Voting Agreement dated as of the date hereof by and among American Cellular
Corporation, and the holders of PriCellular Corporation ("PriCellular") but
only with respect to the shares of PriCellular Series A Preferred Stock we own.

                                       SPECTRUM EQUITY INVESTORS, L.P.
                                        By: Spectrum Equity Associates, L.P.
                                            its general Partner



                                        By:     /s/  Xxxxx Xxxxxxxxx
                                           ------------------------------
                                            Name:  Xxxxx Xxxxxxxxx 
                                            Title: General Partner