Many Singtel mobile users found themselves unable to make calls or access the Internet last night.
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.
Singtel said in an update on its Facebook page at about 11.30pm: "We are experiencing some mobile network issues. Our engineers are investigating and we will provide updates as more information comes in. Thank you for your patience."
At least 200 posts complaining about the lack of calling, text messaging and 4G data services were made since about 10pm.
In a post, user Jess Woo said 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 at the time, before Singtel's post.