Several M1 customers dialling the telco's 1627 hotline yesterday were routed to the police "999" hotline instead.
It was not the result of a prank but a technical issue on M1's end, as police officers told callers.
The problem, which lasted about two hours, was rectified at around 1.30pm yesterday.
In a Facebook post at around 3pm, M1 apologised for the inconvenience caused. "Some calls to our hotline were inadvertently diverted to 999," it wrote.
In a statement late yesterday, M1 said only customers in the eastern part of Singapore and the Central Business District who accessed the Internet between noon and 1.30pm were affected.
A file was configured incorrectly while the telco was tweaking its emergency call feature for 4G voice, which resulted in its hotline being wrongly mapped to the local emergency number.
Customers were advised to reboot their mobile phones to reset the devices, which could have downloaded the erroneous file.
Administrative executive Heng Teng Zhao, 34, who called the M1 hotline at lunchtime, thought it was a prank when the other party identified himself as part of the Singapore Police Force and suggested that Mr Heng call back after lunch.
"This is a serious matter," said Mr Heng. "Imagine clogging the police emergency hotline with unrelated calls."
The Infocomm Development Authority said it is investigating the incident. The police declined comment.
This article was first published on Oct 18, 2014.
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