SINGAPORE - A power-related issue was behind a disruption to Singtel's mobile services that affected many users islandwide for over three hours from around 10pm on Thursday (Oct 18).

The Straits Times understands that it was an internal power issue.

Apologising for the service disruption, the telco said in an update on Facebook at 1.20am on Friday that it detected issues with mobile voice and data services on its 3G and 4G network at 10.11pm.

"Initial investigations indicate that this was due to a power-related issue. Affected services have been progressively restored from 11.50pm and we will continue to monitor the network closely to ensure full restoration," said Singtel.

A Singtel spokesman said on Friday evening that the telco would be offering its mobile prepaid and postpaid customers a day of free local mobile data on Nov 10, a Saturday.

"We regret last evening's service interruption that affected mobile voice, SMS and data services... We apologise for the inconvenience caused to our customers and thank them for their patience," the spokesman added.

While some customers said service was restored for them after Singtel's 1.20am update, others still had issues connecting to the Web on their mobile lines.

The telco said at 2am that, as of 1.22am, all affected services had been restored.

On Thursday night, many Singtel mobile users said they were unable to make calls or access the Internet.

Customers took to Singtel's Facebook page to complain about service disruptions in areas such as Jurong, Bishan, Ang Mo Kio, Bukit Merah, Woodlands, Sengkang and Potong Pasir.

Between 10pm, when users said they started experiencing problems, and about 11pm on Thursday, at least 200 posts complaining about the lack of calling, text messaging and 4G data services were made.

Singtel first posted about the disruption at about 11pm, noting that there were mobile network issues and its engineers were looking into the matter.

In an update at 12.20am on Friday, Singtel said: "We regret to inform that some customers may be experiencing intermittent difficulties accessing mobile voice and data services on the 3G/4G network."

By 1am, Singtel's post about the disruption had attracted about 2,000 comments, about 1,800 reactions - including likes and angry reactions - and some 770 shares.

In a Facebook post before Singtel's update, user Jess Woo said that she had tried to restart her phone multiple times in the last hour.

"Till now no response or official updates from Singtel on their page," she added.

Another user, Chloe Poh, said that she tried to call for a Grab car home after an office event but could not do so. "I could... not use the phone network. This caused me great inconvenience. Please give an explanation," she said.

Legal trainee Angelina Tan Anqi told ST that she relied on her home's Wi-Fi network to surf the Internet.

"I'm not exactly sure when services resumed but when I went to bed at around 1am it was still down," she said.

The 24-year-old added that services were back to normal on Friday morning when she woke up for work.

An IT professional, who wanted to be known only as Mr Sng, said that he experienced issues with data and mobile services from Orchard to Tiong Bahru.

"At about 10pm, there was no (mobile) signal on my phone, no 3G nor 4G... I returned home... but still could not make calls," he said, adding that several of his friends were affected, including prepaid card users. As of 11.20pm, his connection issues were still not resolved.

Another Singtel subscriber, Ms Lim Lee Ren, 25, said that she was not badly affected, as she was at home and could still surf the Web on Wi-Fi.

But Ms Lim, who works in a finance start-up, added: "It would have been problematic if I was out and unable to reply my bosses who need replies 24/7."

A spokesman from telco regulator Infocomm Media Development Authority said it is investigating the incident.

Additional reporting by Timothy Goh