Initial Statement of Beneficial Ownership (3)

EXHIBIT 99.15b

The number of RSUs that vest will be based on the Company's total stockholder return ("TSR") relative to the performance of those companies in the NASDAQ Telecommunications Index (the "NASDAQ Telecom Index") measured over a four year performance period covering fiscal years 2015 through 2018, with one year (fiscal 2015), two year (fiscal 2015 and 2016), three year (fiscal 2015, 2016, and 2017) and four year (fiscal 2015, 2016, 2017, and 2018) performance periods. The TSR for each measurement period will be compared against the period of July 15, 2014 to September 15, 2014.  The RSU award will be divided into four equal tranches, with one tranche assigned to each measurement period. 

The actual number of shares that vest will be determined by the Compensation Committee after the end of each measurement period based on the relative TSR for the period and will range from 0% to 150% of the target amount for that period. In order to vest in 100% of the target number of RSUs, the Company's TSR must be at the 50th percentile of the NASDAQ Telecom Index for each measurement period. If the Company's TSR is above the 50th percentile, the number of shares that vest will increase above the target number by 2% for each percentile above, and if the Company's TSR is below the 50th percentile, the number of shares that vest will decrease below the target number by 2% for each percentile below; provided that no shares will vest if the Company's performance is below the 25^th percentile.

The vesting date will be the date the Compensation Committee determines the number of shares which have vested. The number of RSUs disclosed in this Form 3 reflects 150% of the target amount, or the maximum number of shares that will vest if the full performance criteria are met in all three measurement periods.  Each earned unit converts into one share of common stock on the vesting date.