VoLTE + sending SMS / specify method of sending SMS


May 21, 2019
My Mi9SE struggles to send SMS while VoLTE is enabled. VoLTE works great and the increased call quality is appreciated, however the phone refuses to send SMS. It can receive SMS without any problem.

If VoLTE is disabled, SMS sending works as expected.

I checked with a contact who works at the mobile network and he said it sounds like the phone is trying to send SMS via IP (which is something that the network isn't configured for and they still rely on SMS over control-plane via a SMSC).

Is there a way in MIUI to disable SMS via IP or force SMS over control-plane via SMSC?