TPG Singapore has been on trial since Jan 2019. Although 4G data works for all handsets, voice calls are limited to only a handful of selected handsets that supports VoLTE.
So far, only some Samsung, Huawei, Oppo phones and unsupported Xiaomi works for making voice calls over LTE.
Previously on a report, TPG has highlighted some of the challenges they faced and one of it was to make available VoLTE voice call support on Apple, which has one of the largest market share in Singapore.
We are now seeing some progress as iOS ver 13.1.1 has enabled the VoLTE function for TPG as seen in the screen shot below.
We are unsure if it is beta as it shows this message at the bottom of the first screen. Currently models that work include iPhone 7, iPhone 8, iPhone X, iPhone XS / XS MAX.
“The mobile network has not been certified by the carrier for VoLTE on iPhone. Battery life, calls, text messages, voicemail and mobile data may be affected. “
Give it a try and see if you can make finally make voice calls on iPhone.
Update 30/9/2019 10:00 Reports in that it can only make outgoing calls. Incoming calls do not work.