MMS not working on T-Mobile WiFi

Regrettably, T-Mobile does not grant any third-party messaging apps access to the T-Mobile WiFi Calling feature for MMS. T-Mobile use something called GBA authentication which only system apps or apps digitally signed by T-Mobile can use (so not Textra).

However you can still use Textra to send and receive MMS with T-Mobile, just not via WiFi Calling. 

See Textra Settings > MMS > T-Mobile WiFi Calling Fix

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