Will my Sonim XP3 work after July 1, 2022?

@Mirror and snake if your phone is currently configured for VoLTE it should work, at least for calls and SMS.  If it's still communicating 3G you'll need to turn on VoLTE per my previous post.  Apparently VoLTE is not enabled by default. The "defective device" explanation you were given sounds suspiciously like someone didn't feel like taking the time to troubleshoot.  😉

I also have a Sonim XP3 that I upgraded to from my beloved old Kyocera DuraXT around the time of the Sprint merger because they told me the DuraXT was incompatible with the soon-to-be-upgraded network.  I explicitly chose the XP3 because it WAS supposed to work on the upgraded network.  A couple months later they sent me a letter in the mail telling me I had to "upgrade" again.  After sifting through multiple mixed contradictory messages, I figured out that the XP3 would work IF the VoLTE option was enabled.  The reason why 3G phones had continued to work is because of delays pulling the plug on the 3G network, which now is scheduled for July 2022.  The XP3 definitely IS capable of doing Voice over LTE on the new network, but you have to enable VoLTE to get it going over 4G on the new network.  Settings / Network & Internet / Mobile Network / Voice Networks / VoLTE calls - it'a a toggle switch, and it's greyed out if you're on a call.  You have to be disconnected from all calls before you can turn it on.  After you turn it on the indicator on the top of the screen immediately to the left of the signal bars should say "VoLTE" with "LTE" also above the signal bars.  If it says "3G" you need to turn it on or the phone will no longer be able to make and receive calls whenever they finally deep-six the 3G network.

That said, I am still having problems sending and receiving MMS (picture) messages on the XP3 over T-Mobile.  SMS (text only) works fine.  MMS used to work with this phone.  Last MMS I successfully received on it was on 05/05/2021.  I currently have support tickets open with both T-Mobile and Sonim on this issue.  In the meantime I just tell my contacts if they want to send me pictures, send them over Telegram or other instant messaging apps that I can access from my computer or tablet.  Most of the MMS I get these days seems to be from political fundraisers who just want money, and they can go to /dev/null anyway AFAIC.

I talked to someone at a T-mobile store and he determined that my phone is malfunctioning because it has a defect. Of course it is too late to trade in for a new one, so I'm just stuck with this problem. 😒

MyCommID, This problem happens in places where my phone normally allows me to talk, text, and use data just fine. It even happens in places where I can also use wifi, like at home.

By the way, T-mobile does offer the XP3, or at least it did at the time I bought mine about a year ago, and they still offered it the last time I was on this site (late April 2022, about nine days ago; I am too lazy to check today).

Mirror and Snake—— the only thing that might be an issue is if you perhaps are frequently or at critical moments outside if the LTE range?

Others, I have the same question as Mirror and Snake. Seems like smoke and mirrors and I am quite annoyed. Plus the automated phone system won't put me through to a person to discuss it.
 

TMobile was trying to force a new phone purchase saying 4g was required or just not properly explaining itself?

The XP3 is VOLTE.  It says so in the screen itself. Our sonim purchased just months before tmobile started telling us it needed to be replaced. I don't think the plus was out yet and all tmobile had to offer at that time last year in flip phone was an Alcatel. We switched to sonim because the Alcatel was a bad phone and we're not going back to one.
 

As noted above the xp3 continued to work into this year. So seems like hype to me still. Tmobile never offered the sonim xp3 (was sprint model) so maybe they don't understand it's bands or otherwise just want to sell xp3 plus stock? 
 

I’m. waiting until July 2 to see if tmobile is wrong, as I suspect it is.  (But I do have a backup if that phone does stop working until I can replace with later model)

Thanks fireguy. Do you happen to know whether the Sonim XP3 has this capability? It's marketed as a 4G LTE phone...

because your calls and regular texts are sent/received over 3G..so unless your phone has VoLTE (Voice over LTE) you wont be able to make/receive calls or send/receive regular texts..