SINGAPORE — Full restoration of M1’s 3G services will only be completed by midnight, even though the telco’s engineers are “working flat out” to restore network coverage, in the longest outage to hit mobile phone users here so far.

The outage, caused by a power incident, began at 3am on Tuesday.

Asked why the repairs are taking so long, M1 said: “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.”

M1 had said on Tuesday that the disruption affected customers in the “south-western parts of Singapore, namely West Coast, Jurong and Tuas areas”.

Customers, however, said the disruption was more widespread, reporting outage in areas across the island. Yesterday, customers in places like Tampines, Paya Lebar, Sembawang and Woodlands reported they still had no 3G service, while others had intermittent service.

M1 did not respond to queries as to why more areas were hit by the outage than it had stated.

And although M1 said the outage only affected its 3G network, users had reported that basic cell coverage was down as well.

Many were unable to make calls, and text messages were received hours after being sent. Some even picked up coverage from Malaysian and Indonesian service providers like Celcom, Telkomsel and AXIS, which M1 said could be due to “signal spillage” from neighbouring countries.

Mr Chong Wei Xiang, 26, was in Yew Tee at about 3pm yesterday when his mobile phone’s network suddenly switched from M1 to a Malaysian telco. He was on a call with his boss when the line went dead.

“I wanted to ask for the timing of my shift tomorrow,” said Mr Chong, who works as an F&B crew member. “The line cut off. I was saying: ‘Hello? Hello?’ but it was gone.”

Mr Chong rushed to his home in Yew Tee to use his landline telephone. To his relief, he managed to contact his boss. When his parents managed to reach him, they told him his phone appeared to be on a foreign network as they heard an operator’s message in Malay.

M1 said customers should set their networks to manual search mode, to avoid automatically switching to another network.

Irate M1 customers left hundreds of comments on the telco’s Facebook page, saying they were still affected by the outage which, at press time, had lasted for more than 40 hours — the longest continuous mobile service outage in Singapore. The telco had a 12-hour continuous disruption in May 2011 — which was the previous record.

Yesterday, the Infocomm Development Authority (IDA) said it was “concerned” about the disruption and was “closely monitoring” the restoration effort.

“The IDA has urged M1 to make every effort to restore its services as quickly as possible to minimise inconvenience to its subscribers. M1 should also update the public regularly, while its engineers work to fully restore services,” it said.

For contravening the Code of Practice for Telecommunication Service Resilience, the IDA can fine a telco up to S$1 million or 10 per cent of its annual turnover, whichever is higher.