M1 customers who are still holding on to their old 3G plans with the generous 12GB mobile data allowance are in for a treat.
The telco has upgraded them to its 4G network at no extra charge.
These customers have resisted signing up for the faster 4G plans as they cost more for a similar-sized data allowance.
M1 chief marketing officer P. Subramaniam told The Straits Times: "We had a small number of customers still on legacy 3G smartphone plans. 4G was recently activated for these customers, to enable them to enjoy the best experience on our 4G network."
4G mobile networks are said to offer about four times faster surfing than 3G ones. 4G networks can also pack up to five times more data, allowing more people to connect without slowing down surfing speeds.
M1 would not say how many of its 1.2 million post-paid customers are still on 3G plans with the 12GB data allowance. But The Straits Times understands that "thousands" of them have already been notified about the automatic upgrade.
Public relations consultant Khairul Sufiyan, 30, said he received the SMS notification earlier this week.
He has resisted renewing his telco contract, even with the promise of mobile phone subsidies, because he wants to keep his current 3G plan that comes with 12GB of mobile data.
The plan costs about $50 a month, compared with a similar 4G plan without contract from M1 that costs at least $70 a month.
"I'm glad my years of waiting have paid off," said Mr Sufiyan, adding that surfing on his phone is noticeably faster after the upgrade.
However, if customers sign a 12-month contract with M1, they pay $51 a month for a plan that comes with 14GB of mobile data allowance.
Mr Ramakrishna Maruvada, a telecoms researcher at Daiwa Capital Markets, said M1's move is an attempt to improve customer loyalty.
"This is a vulnerable group; their refusal to upgrade indicates they are value seekers and are likely to switch operators when a value deal shows up," he added.
He expects Singtel and StarHub to do the same.
The latest figures from regulator Infocomm Media Development Authority show there are four million post-paid 4G users across the three telcos - Singtel, StarHub and M1 - compared with just 890,800 post-paid 3G users.
Mr Clement Teo, principal analyst at market research firm Ovum, said moving subscribers to just one network would help telcos focus their resources on their 4G networks.
When contacted, StarHub's head of product Justin Ang said it will monitor the situation and "evaluate the best upgrade options" for its 3G customers.
Singtel said 3G customers need to sign new contracts for 4G plans to get 4G speeds.