As M1 takes a very serious view of the service outage which affected customers from 15 to 17 January 2013, the telco has provided more information on the consequent recovery activities.
The power incident at one of its network centres was caused by sparks at the distribution rack when a vendor attempted to connect the power cables from the transmission equipment rack to the distribution rack during the transmission equipment upgrade.
Smoke emitting from the transmission equipment rack and the distribution rack triggered the FM200 gas suppression system, which discharged gas. This resulted in one of the 88 water sprinklers being activated, causing damage to one of its mobile network switches and led to the service disruption.
M1’s top priority was to restore service in the affected areas as quickly as possible and contingency plans were activated. To restore service, contingency plans for the core network was to increase network capacity and signaling links between all the other mobile network switches.
Plan A for the radio network was activated, with the radio network controller and its associated media gateway being re-linked to the alternative mobile network switch. While the links were being re-configured, Plan B was concurrently activated. This involved complex step-by-step restoration work including the reconfiguration of 416 base stations to the alternative mobile network switch, re-establishing communication links, and traffic rebalancing.
This was followed by comprehensive testing, including drive tests in the coverage area of each individual base station, to ensure full call continuity for both voice and data services. Plan B resulted in a total of 199 sites being connected by 3am on 17 January 2013. Plan A took over and completed the remaining 217 sites.
Partial 3G service to customers in the affected areas was restored on the evening of 15 January 2013. Restoration works for all affected sites were completed at about 3pm on 17 January 2013 and full service was restored at 6pm on the same day.
M1 would like to reassure customers that its contingency plans were in place and were activated in this incident. As a result, it was able to restore service in the shortest possible time under the circumstances. In the absence of these contingency plans, the services would have taken about 12-16 weeks to be fully restored. Plans to further enhance and improve our network resiliency incorporating the latest technology commenced in the second half of 2011, with target completion date of mid-2013.
To express its sincere appreciation to the affected customers for their patience and understanding, M1 is offering all postpaid customers three days of free local mobile calls, SMS, MMS and data services from 10 to 12 February 2013. This will commence from 00:01 hours on 10th February till midnight on 12th February 2013. M1 prepaid customers will enjoy a S$1 bonus for every top-up of S$17 and above, during the month of February 2013.