Voice on Nokia 225 no longer working.

I have the same exact problem as PineApples and Finlator to the letter.  Nokia 225 4g.  T-Mobile account is only Talk and Text… no data.  225 has VoLTE abilities and has been working fine for about a year without any data plan and no way to update itself with a newer software version.  Did a full reset / wipe with no change.  If you attempt to make a call now and wait, you can watch the LTE 4 bars dwindle from five bars to zero bars and the LTE will switch to E and it MIGHT connect with a single bar on E if there is an old tower nearby, but it is very rare and unstable if it does connect.  If I go into the settings and change the network type to "3G/2G", it doesn't go through the attempting to use LTE, but only throws up one bar and just as unstable and rare.  Something certainly seems like it changed on the T-Mobile end.  Any chance the default APN the phone/sim comes with has changed… could it be fixed with a corrected APN if VoLTE is the primary way the 4g voice works?  Just an idea.