System Availability

2018

Month Overall System Availability Unique System Availability Phone Number System Availability
December 99.986928% 99.988424% 99.985432%
November 99.999381% 99.999997% 99.998766%
October 99.999998% 99.999997% 100.000000%
September 99.999950% 99.999999% 99.999902%
August 99.999969% 100.000000% 99.999939%
July 99.999885% 100.000000% 99.999771%
June 99.999645% 100.000000% 99.999291%
May 99.999693% 99.999736% 99.999650%
April 99.999344% 99.999993% 99.998696%
March 99.999681% 100.000000% 99.999363%
February 99.991943% 99.999998% 99.983888%
January 99.999637% 99.999604% 99.999671%

2017

Month Overall System Availability Unique System Availability Phone Number System Availability
December 99.999519% 100.000000% 99.999038%
November 99.999991% 100.000000% 99.999983%
October 99.999381% 99.999997% 99.998767%
September 99.996449% 99.993055% 99.999843%
August 99.993447% 99.999845% 99.987049%
July 99.999878% 99.999757% 100.000000%
June 99.999896% 99.999795% 99.999997%
May 99.999982% 99.999993% 99.999972%
April 99.999999% 99.999999% 100.000000%
March 99.999999% 99.999999% 100.000000%
February 99.987789% 99.988546% 99.987032%
January 99.997484% 99.994979% 99.999991%

2016

Month Overall System Availability Unique System Availability Phone Number System Availability
December 99.999998% 99.999997% 100.000000%
November 99.999998% 99.999999% 99.999997%
October 99.999982% 99.999966% 100.000000%
September 99.999989% 99.999979% 100.000000%
August 99.997383% 99.999773% 99.994994%
July 99.897372% 99.999945% 99.794801%
June 99.999999% 99.999999% 100.000000%
May 99.999608% 99.999217% 100.000000%
April 99.999954% 99.999909% 100.000000%
March 99.999670% 99.999341% 100.000000%
February 99.998067% 99.996136% 100.000000%
January 99.999470% 99.999886% 99.999054%

2015

Month Overall System Availability Unique System Availability Phone Number System Availability
December
99.999812% 99.999625% 99.999999%
November
99.999999% 100.000000% 99.999999%
October
99.997298% 100.000000% 99.994596%
September
99.999114% 99.999110% 99.999117%
August
99.999750% 99.999500% 100.000000%
July
99.994312% 99.999966% 99.988658%
June
99.992820% 99.994841% 99.990800%
May
99.995936% 100.000000% 99.997968%
April
99.999665% 100.000000% 99.999330%
March
99.992382% 99.999894% 99.984871%
February
99.999707% 99.999554% 99.999861%
January
99.999268% 99.999465% 99.999072%

2014

Month Overall System Availability Unique System Availability Phone Number System Availability
December
99.985587% 99.972626% 99.998548%
November
99.999826% 99.999983% 99.999669%
October
99.947976% 99.999780% 99.896172%
September
99.999640% 99.999279% 100.000000%
August
99.998388% 99.996783% 99.999993%
July
99.993415% 99.986880% 99.999949%
June
99.988632% 99.977344% 99.999921%
May
99.998572% 100.00000% 99.999286%
April
99.982503% 99.978948% 99.986059%
March
99.996552% 99.997722% 99.995382%
February
99.999080% 99.998610% 99.999550%
January
99.999611% 99.987315% 99.993463%

2013

Month Overall System Availability Unique System Availability Phone Number System Availability
December
99.971279% 99.992504% 99.981892%
November
99.684396% 99.979263% 99.850650%
October
99.856029% 99.999236% 99.834083%
September
99.948076% 99.984747% 100.000000%
August
99.736350% 99.535574% 99.999998%
July
99.951797% 99.903593% 100.000000%
June
99.935056% 99.899067% 100.000000%
May
99.987209% 99.996913% 99.999811%
April
99.974103% 99.953704% 99.999088%

 

The system availability is computed by Total Downtime (TDT), estimated from the total number of affected Unique and Phone number during system failure and maintenance, and Total Operation Time (TOT).

Formula for System Availability:
Total system availability = (1- (Unique & Phone Number’s TDT / Unique & Phone Number’s TOT)) × 100

 

Formula for Unique System Availability:
Unique system availability = (1 – (Unique’s TDT / Unique’s TOT )) × 100

Formula for Phone Number System Availability:
Phone Number’s system availability = (1 – (Phone Number’s TDT / Phone Number’s TOT)) × 100