NPAC/SMS Throughput Milestones and Modifications

NPAC/SMS Throughput Milestones and Modifications

1. Purpose of Plan. This Performance Plan specifies the requirements relating to transaction throughput performance of the NPAC/SMS. The NPAC/SMS Functional Requirements Specification (the “FRS”) and the NPAC/SMS Interoperable Interface Specification (the “IIS”) provide for certain throughput performance requirements of the NPAC/SMS that are based on CMIP operations per second by the NPAC/SMS (the “FRS/IIS Specs”). The FRS/IIS Specs include in the FRS at section 6.4.2 (Interface Performance Requirements), Requirements R6-29.1 and R6.29.2 (business objective to activate 25 TNs per second) and Requirements R6-28.1 and R6-28.2 (maximum SOA transaction rates), which requirements are internally inconsistent.

2. NPAC Throughput. The throughput performance of the NPAC/SMS (the “NPAC Throughput”) shall be stated in telephone numbers (“TNs”) per second.

2.1 User System Congestion. User System Congestion is defined as a state of degraded system performance resulting if any of the following conditions occur:

(a) If the NPAC/SMS receives an indication from a User SOA/LSMS that it is unable to receive anymore messages;

(b) If the NPAC/SMS’s retry timer expires for an outstanding operation (download or other message) previously transmitted to a User SOA/LSMS.

(c) If a User SOA/LSMS causes substantial latencies in message flows from the NPAC/SMS as a result of chronic delays in sending responses to the NPAC/SMS that are nevertheless sent in such time as the timers in the NPAC/SMS do not expire. (For example, congestion must address the effect of chronic slow SOA/LSMS responses which are expected on a 3 second basis but for which the timer doesn’t go off until 2 minutes have passed.)

3. Requirement to Avoid Chronic Congestion Slowdown. The ability of the NPAC/SMS to meet the required NPAC Throughput is dependent on User LSMS and SOA systems meeting the implied standards of this performance plan implemented consistently with the IIS for download capacity.

4. Dynamic Throughput Milestones. The minimum required NPAC Throughput (the “Minimum NPAC Throughput”) shall initially be as provided in the following section and shall be revised from time to time as provided below.

4.1 Initial NPAC Throughput Milestones. The required Minimum NPAC Throughput shall be 2.9 TNs per second for all quarters during the period through and including December 31, 1998. Commencing with the quarter beginning January 1, 1999, Minimum NPAC Throughput shall be the number of TNs per second as set forth below, beneath the corresponding calendar quarter (starting with the first day of each January, April, July and October and continuing through the last day prior to the beginning of the next calendar quarter).

Initial NPAC Throughput Milestones

4.1.1 Maximum Value for Minimum NPAC Throughput. The maximum value of a Minimum NPAC Throughput milestone is 25 TNs/sec.

4.2 Demand Forecasting . The Minimum NPAC Throughput shall be adjusted from time to time based on system demand trend experience and current industry intelligence. System demand stated in TNs per second (“Projected Demand”) shall be forecasted on a quarterly basis using data for activity through the most recently completed calendar quarter, and shall be determined, initially, by the industry demand model provided below.

For purposes of demand trending and forecasting the following terms shall have the following meanings:

4.2.1 Available TNs (TN) means number of working and reserved TNs resident in LNP-capable switches (those switches that are currently LNP capable or that are planned to become LNP capable during the calendar year of the calculation) in the region. An assumption of an NPA-NXX fill rate of 50 % was used in the initial calculation of Projected Demand. This assumption will be adjusted periodically when more accurate data is available.

Two known pending significant impacts to the number of Available TNs include the implementation of Number Pooling and the inclusion of Wireless services to the NPAC/SMS.

4.2.2 Incremental Penetration Rate (IPR) means the percentage of available TNs which actually port for the first time (i.e. move outside of their donor network) during the forecast period, forecasted quarterly on the basis of the four consecutive quarters just ended and current industry projections.

4.2.3 Incremental new TNs ported this year (INTN) means available TNs multiplied by incremental penetration rate.

INTN = TN * IPR

4.2.4 Cumulative new TNs ported by mid-year (CNTN) shall be calculated on an annual basis at the close of the calendar year, and means cumulative TNs first ported (not including subsequent ports of the same number) through the end of the all calendar years then ended plus one-half of incremental new TNs first ported during the calendar year just ended. This number shall then established for the third quarter of the current year with all other quarter determined by linear interpolation.

CNTN = åcurr yr -1 INTN + ½ INTNcurr yr

4.2.5 Churn Rate (CR) means a percentage equal to the number of TNs that are ported for a second or subsequent time during the forecast period. Churn Rate shall be forecasted on a quarterly basis.

4.2.6 Annual TNs ported due to churn (CRTN) means churn rate multiplied by cumulative new TNs ported by mid-year.

CRTN = CR * CNTN

4.2.7 Total TNs ported this year (TTN) means incremental new TNs first ported this year plus the product of (a) annual TNs ported due to churn divided by 12, times (b) the number of months completed in the calendar year through the end of the most recent calendar quarter. This shall be calculated on a quarterly basis.

TTNs = INTN + (Current Month*CRTN/12)

4.2.8 TNs ported per month (MTN) means total TNs ported this year divided by the number of months elapsed in the calendar year through the close of the most recent calendar quarter. This shall be calculated on a quarterly basis.

MTN = TTN / Current Month

4.2.9 Number of busy days per month (BDM) means the number of busy days shall equal the smallest number of days necessary to account for 75% of all porting activations. This number will be forecasted on a quarterly basis. The initial estimate of this parameter is 8.

4.2.10 TNs ported per busy day (BDTN) means TNs ported per month divided by the number of busy days per month.

BDTN = MTN / BDM

4.2.11 Percentage of day’s traffic per busy hour (BH%) means with respect to busy days, the percentage of the entire day’s porting activations which take place in the busiest one-hour period on that day. This number will be forecasted on a quarterly basis. The initial estimate of this parameter is 36%.

4.2.12 TNs ported per busy hour (BHTN) means TNs ported per busy day multiplied by percentage of day’s traffic per busy hour.

BHTN = BDTN * BH%

4.2.13 Projected Demand (or Demand TNs per second) (PD) means TNs ported per busy hour divided by 3600 seconds/hour

PD = BHTN / 3600

The initial milestone values reflected in section 4.1, were derived from the initial iteration of the Projected Demand model depicted below. These numbers are derived from the West Coast region. The italicized lines reflect the five (5) input parameters of the model.

4.3 Revision of Minimum NPAC Throughput. Projected Demand as calculated quarterly, beginning 7/1/98, shall be compared to the Minimum NPAC Throughput for the calendar quarter (the “Adjustment Quarter”) commencing on the first day of the seventh month following the close of the quarter on which the Projected Demand calculation is based. If the difference between the Projected Demand and the Minimum NPAC Throughput for the Adjustment Quarter is at least 10% of the Minimum NPAC Throughput then in effect for the Adjustment Quarter, the Minimum NPAC Throughput for the Adjustment Quarter shall be revised to equal the Projected Demand, but in no event shall the adjustment result in a Minimum NPAC Throughput that is (a) less than 2.9 TNs/sec, (b) less than the previous quarter’s milestone, or (c) greater than the lesser of (i) two times the Minimum NPAC Throughput as in effect at the close of the calendar quarter on which the Projected Demand calculation is based or (ii) 25 TNs/sec.

CONFIDENTIAL

EXHIBIT N-1