Originally Posted by grentuu
Hangouts does not work with Wifi Calling MMS on Tmobile.
Searching "htc one m8 google play edition wifi tmobile mms" yields tons of discussions of problems.
Apparently tmobile will not allow 3rd party text apps to take advantage of MMS on wifi only.
The only solution appears to be using "stock messaging" to send MMS on wifi. But GPE does not have "stock messaging" only hangouts.
However, Tmobile has told me the GPE does not support wifi calling at all, so I'll be sending it back.