Many StarHub customers were cut off from mobile services for up to 81/2 hours yesterday, in what is the second major mobile disruption here this year after M1's.
In a statement on Facebook at 6.20pm yesterday, the telco said network services had been fully restored.
Customers first reported problems while making and receiving calls as early as 9.30am.
StarHub first acknowledged the problem on its Facebook page shortly after 11am, saying only that voice services of customers in the eastern and western parts of Singapore were "intermittently" disrupted. It also maintained that mobile data and SMS services were not affected.
But users in the northern and central areas - including Bukit Batok, Ang Mo Kio, Woodlands, Orchard Road, Novena and Clarke Quay - also complained about connection problems.
Community relations executive Hng Hwee Ling, 28, said she was talking to a friend over the phone during lunchtime when her line was cut off. She was in Bukit Batok Central.
"I thought the problem was with my phone. I rebooted it a couple of times," said Ms Hng, whose connection was restored at 3pm.
Pockets of users also complained about not having data connection, prompting StarHub to say in its statement later in the evening that it would investigate if its mobile data services were down too.
Warehouse administrator Ling Chua, 21, said she was unable to get data connection on her company-issued mobile phone for several hours in the afternoon, in addition to having voice call woes.
"I couldn't talk to my clients for more than two minutes without being cut off," lamented Ms Chua, who works in Pasir Panjang.
Industry regulator the Infocomm Development Authority said in a Facebook post at around 4.30pm that it was investigating the issue.
Some users could use SMS and messaging apps like WhatsApp, although their voice services were disrupted.
"Still, it was frustrating as I had to coordinate a department offsite meeting at Clarke Quay," said teacher Elsa Chen, 28. She ended up borrowing her friend's phone to make calls.
The last major mobile outage was in February, when many M1 users were unable to make calls for six hours.
This was due to call congestion that arose from equipment experiencing intermittent connection problems while authenticating mobile users.
This was not related to the record 71-hour mobile service disruption in January last year, for which M1 was fined $1.5 million.
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