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                                                                   Exhibit 10.21

                              FRONTIER CORPORATION

                        MANAGEMENT STOCK INCENTIVE PLAN

                                Amendment No. 2


          Pursuant to Section 14, the Plan is hereby amended, effective as of
the dates and under the conditions specified below, by deleting current Section
9(a) and substituting in its place the following:

     (a)   Options
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               If the employment of a participant terminates by reason of the
     participant's disability or death, any option may be exercised, in the case
     of disability, by the participant or, in the case of death, the
     participant's designated beneficiary (or personal representative if there
     is no designated beneficiary) at any time prior to the earlier of the
     expiration date of the option or the expiration of one year after the date
     of disability or death, but only if, and to the extent that the participant
     was entitled to exercise the option at the date of disability or death.  If
     the employment of a participant terminates on account of retirement, all of
     the participant's outstanding options shall become immediately vested and
     these options together with previously vested but unexercised options may
     be exercised prior to the earlier of the expiration date of the option or
     the expiration of 13 months from the date of retirement.  For this purpose,
     "retirement" means any termination of employment on or after a participant
     is entitled to receive an early retirement benefit under any defined
     benefit pension plan maintained by the Company or an affiliate in which the
     participant has any accrued benefit.  If the participant does not have an
     accrued benefit in any such plan, "retirement" means the participant's
     termination of employment on or after he has reached age 55.  Upon
     termination of the participant's employment for any reason other than
     retirement, disability or death, all nonvested options held by the
     participant shall be forfeited and any options that are vested on the date
     of termination may be exercised prior to the earlier of the expiration date
     of the option or the expiration of 90 days from the date of termination.
     An option that remains exercisable after the expiration of three months
     from termination of employment shall be treated as a NQSO after three
     months even if it would have been treated as an ISO if exercised within
     three months of termination.  Notwithstanding the foregoing, an option may
     not be exercised after retirement if the Committee reasonably determines
     that the termination of employment of such participant resulted from
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     willful acts, or failure to act, by the participant detrimental to the
     Company or any of its subsidiaries.

     Effective Dates:  The reduction, in the first sentence, from three years to
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          one year in the right to exercise options following disability is
          effective for options granted after December 31, 1998.

                    The definition of retirement, in the new third sentence, is
          effective January 1, 1999.

                    The provisions in the second sentence for the vesting and
          exercising of options on account of retirement are effective for
          options granted after December 31, 1998.

                    The provisions in the fifth sentence concerning the exercise
          of options upon termination of employment for reasons other than
          disability, death or retirement are effective January 1, 1999.


     IN WITNESS WHEREOF, the Company has caused its duly authorized officer to
execute this amendment on its behalf this 9th day of December 1998.

                                        FRONTIER CORPORATION

                                        
                                      /s/ Barbara J. Laverdi
                                  By ---------------------------
                                          Barbara J. LaVerdi

                                  Title:  Assistant Secretary