Please tell us some basic information before asking for help:
Model Name: ROG 5
Firmware Version: WW-31.0810.1226.139
Rooted or not: Not rooted
Frequency of Occurrence: Always
APP Name & APP Version (If your issue relates to the app): Phone calls
In addition to information above, please also provide as much details as you can, e.g., using scenario, what troubleshooting you've already done, screenshot, etc.
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For almost a year (from ~Nov 2021 till ~Oct 2022 or so this year), with Australian mobile carrier Telstra (and by extension its retail MNVO, Boost), ROG 5 used to work very well with VoWiFi (aka WiFi calling). Then recently, it's stopped working. (VoLTE still works though; so the problem is limited to VoWiFi only at this stage.)
Can this problem be fixed ASAP please? This is an essential functionality of a phone for me.
Living in an outer suburb with terrible mobile signal coverage inside home, this is causing me grief (in terms of mobile call quality being terrible and unreliable). When VoWiFi was working, due to being connected to strong WiFi network based on a fast/reliable fibre Internet connectivity, phone calls inside the home used to be always great. But not anymore!
I've proven that the SIM itself delivers VoWiFi on a Motorola Moto G 5G phone. So SIM and mobile operator are clear in this case.
(I'm asking around for Optus & Vodafone-TPG SIMs to see whether this VoWiFi breakage is limited to Telstra.)