Xperia 1 V - IMS registration randomly de-registered

[Maki8877]

Good day, I am currently using an Xperia 1 V (US) and all features including 5G are working as intended. IMS was registered up until a few days ago and I was able to use VoLTE, so the hardware shouldn't be a problem. However, it randomly de-registered and my calls switch to 3G now. I have spoken to Telus support and all I'm given are the usual reset network settings and turn off and on phone solutions. I'm then always told that they can't help me because it is not a Telus phone despite VoLTE clearly working up until a few days ago. They also told me 5G wouldn't work as I'm using it. Is there a fix for this?

[FuzzyLogic]

Not sure of the validity of this but this but it may offer a clue:

In general, all Canadian providers only enable VoLTE on a specific list of phones that they sell and support. For the past several years, this has excluded almost all Sony phones on most providers. If you're looking at a model that isn't for sale in Canada (you have to import it), then it's definitely not available. There's no good reason for this, the phones and networks are both perfectly capable. Apparently some people have managed to convince the network support to enable it on their phone, but that's more a case of getting lucky with a support agent who doesn't know/care or tricking them into enabling it 😕

Source Volte support and 5G for 1V Canada : r/SonyXperia (reddit.com)

[xray]

This has been a long standing issue

https://forum.telus.com/t5/Ideas/Open-up-wifi-calling-for-all-compatible-devices/idi-p/129802

https://forum.telus.com/t5/Mobility-Devices/Does-Telus-support-One-Plus-devices/m-p/96414

https://forum.telus.com/t5/Mobility-Devices/Telus-Doesn-t-Support-VOLTE/m-p/133348

[Syaoran]

This is intentional! Telus and Bell more so than Rogers but they are all doing it in Canada. They will even go as far as to block your roaming in the US and internationally, which is what they did to me with a T-Mobile USA purchased s23 Ultra. A CCTS complaint finally was settled after I moved my 6 lines to Rogers where my OnePlus 8T and s23 Ultra fully work without any issues being provisioned for VoLTE, WiFi Calling, 5G, and roaming. Telus ate the device balances for the two phones I got to keep because they left me no option but to leave, jeopardizing my safety by even blocking 911 access while roaming!