Sending/receiving MMS not working over WiFi

Like many of the others on this thread, I bought my Kyocera flip phone in 2022 when we were with Verizon.  It is paid and unlocked.  December 2023 we switched to t mobile.  I am not able to open any MMS texts.  over the past 2 weeks, I was on the phone, chat and in stores with various t mobile, verizon and kyocera techs.  We changed settings, checked networks, considered resetting etc, and finally the Kyocera rep explained that Verizon removes a MMS feature when you leave and I guess t mobile does not use it.  So, we have to buy a new t mobile phone….  

I also just discovered that I cannot retrieve any of my voicemails and cannot set up my voicemail.  

I also found that t mobile charges for an outgoing conference call that was always free with Verizon

Like the other customer, I am ready to switch back to Verizon but my husband gets better reception on his phone from t mobile.  

If they want Verizon business, T mobile should offer to replace my phone with one that works in their system.