Voice on Nokia 225 no longer working.

I purchased the Nokia 225 4g as a cell phone for my elderly mother after her previous phone aged out of the 2g network.  The primary requirements were simplicity, reliability, and most of battery life.  The classic Nokia Feature Phone was a good replacement since if she forgot to plug it in for a week, it would still have battery life, unlike most all smartphones. Style, apps, and internet access are not required

The plan I have for it is a Pre-Paid Talk and Text only plan that is no longer offered.  Exactly what she needs and the cost to me is minimal since she only really uses it for emergencies.  The previous phone did still work, though very weakly and intermittently, on the 2g network at her home and I purchased the Nokia for the 4g ability when I found she couldn't call out from her doctor office for a pickup.  It worked excellently for months, but now the Nokia times-out of the 4g network when making voice calls and MIGHT connect to 2g, and then if is does, the signal is still flaky at best and often drops.

I'm thinking that T-mobile wanted/needed to make a VoLTE change that wouldn't affect (or perhaps would help) the majority of their userbase and didn't consider our tiny segment of users that would be cut off.  Or perhaps they did know it and were either willing to lose us for the greater good or were being evil and hoping it would force us to pay for one of THEIR phones ($) and/or move to an account with a data plan ($) and, hey, if we weren't willing to do that, then fine, leave, we weren't making much money off you anyway.

I would be very surprised if, for the above reasons, they put any real effort into fixing the problem affecting the Nokia 225 4g users.  The cost in time and people power would not outweigh the cost of losing a speck of users.  I wonder if this is an issue with other non-Nokia 225 users using the same plan setup.  I'm guessing that the two or so feature phones T-Mobile Prepaid does sell must still work on their network somehow.  It would be a smart move on T-Mobile's part to reach out and say, "Hey, Mr. Hazel Ra… You've been a uninterrupted T-Mobile customer of ours for the last 18 years… sorry for the inconvenience we've caused you through no fault of your own.  Here's the cheapest refurbished phone we sell that will continue to work on your plan, we'll ship it to you for free.  Thank you for being a loyal customer… tell your friends about us!"

That last part was to you, T-mobile, just in case you missed the subtlety.