Singapore's smallest telco M1 has suffered a partial disruption on its 3G network, preventing some of its customers from using services such as voice and data since Tuesday morning.
In a statement Wednesday evening, the telco said full restoration of its network was only expected by Thursday midnight.
"Our engineers are working flat out to restore the network. This complex restoration work involves loading the configuration for each base station into the working switch and comprehensive testing, which includes drive tests in the coverage area of each individual base station to ensure full call continuity for both voice and data services," said M1 in a Facebook post.
In a statement Tuesday evening, the telco explained that during a transmission equipment upgrade by one of its vendors at 3am, a power incident at its network centre set off the gas suppression and water sprinkler systems, which in turn caused an outage to one of its mobile network switches.
M1 added this affected the 3G network entities connected to the switch and resulted in the loss of 3G mobile services to some customers in the South-Western parts of Singapore, namely West Coast, Jurong and Tuas areas.
The telco explained the 2G network entities are connected to another switch and as such, were not affected. This allowed 3G phones of affected customers to automatically switch to the 2G network, but the majority of 4G phones would require customers to turn off the 4G service manually in order to log on to the 2G network.
"We sincerely apologise to our affected customers for the inconvenience caused, and thank them for their support, understanding and patience. Please be assured that our top priority is to resolve this issue as quickly as possible," said Karen Kooi, CEO of M1, in the statement.
She added extra measures would be put in place to prevent a recurrence.
To restore services, M1 said it had connected the network entities to a working switch and are conducting the final stages of testing, with actual migration of traffic from the affected switch to take place progressively.
Frustrated users complain over social media
In a Facebook post at around 6am Tuesday, the telco had advised customers to switch their devices from its 3G network to its 2G one, and promised further updates when full service was restored.
"One of our mobile network switches is impacted by a power problem and mobile services to some of our customers may be partially affected. We are in the process of restoring service and apologise for the inconvenience," M1 said in the post.
4G services for some users appeared to have been hit as well, according to comments on the post.
Affected areas included Pasir Panjang, Tuas, Tiong Bahru, Bukit Batok, Jurong West, Jurong East, Queenstown, Clementi, and Boon Lay, the users added.
One M1 customer, Lim May-Ann, a research director, told ZDNet it was "super annoying" for her.
"It sucks for me--I nearly couldn't get into my Gmail account because the One-Time Password SMS wouldn't come through for about 10 minutes!" she said.
In another comment in a separate post, Samuel Wee said: "[It's] cool. at least M1 is quick to respond and not beat around the bush about the flaw."
In response to ZDNet queries, a M1 spokesperson said: "Our engineers are still working with utmost urgency to restore full service and part of this process is to divert traffic to another switch."
In response to ZDNet queries, ICT regulator Infocomm Development Authority of Singapore (IDA) said M1 had reported the service outage incident to it and was providing advice to customers through its corporate Web site, Facebook and its hotline.
"IDA will investigate the service outage case thoroughly under the Code of Practice for Telecommunication Service Resiliency and take the necessary actions if there is a breach of the Code," said an IDA spokesperson.
M1's partial network outage comes just after a month when all three telcos--including SingTel and StarHub--were fined by IDA for poor 3G coverage. They were each slapped with a S$10,000 (US$8,911.40) fine for non-compliance with the recently tightened Quality of Service (QoS) standards to provide at least 99 percent service coverage nationwide.
M1 had also been fined S$300,000 (US$232,320) in November 2011 following a network disruption in May 2011, when the telco's subscribers in the western region of Singapore had difficulties in making and receiving calls, and accessing SMS, MMS and mobile data services via their mobile devices.
updated 5.49pm, Jan. 15 with M1 statement
updated 6.16pm, Jan. 15 with IDA statement
updated 6.30pm, Jan. 15 with M1 statement