Calls no longer working on previously working Moto phones

[GeraldBr_117368]

Just over two weeks ago, my wife's Moto G9 Plus phone stopped being able to receive or make phone calls with her Smarty SIM. Everything else worked, including SMS, just no phone calls in and out.

I reset everything on the phone, tried my known working Smarty SIM in it, but nothing worked. Her SIM worked fine in mine, so I assumed that the phone had developed a fault and I got her a new one, as the phone is over 3 years old now.

Came to today and I was sorting a spare Moto G7 Power phone for my daughter, got her a new Smarty SIM and exactly the same issue was happening with this phone. As this was a different phone, I don't believe in coincidence, so I tried an EE SIM and calls (and everything else) were/are working absolutely fine.

Can anyone advise as to what the issue is here?

[JJP2RidesAgain · Accepted solution]

Are you in the Midlands ? There have been plenty of threads recently about Smarty turning off their 3G network in the Midlands, and older phones not having VOLTE (AKA 4G CALLING) capability on Smarty. 

[GeraldBr_117368]

Thanks, I've seen Three's shutdown map for the Midlands and we are in that area. And because Smarty's bearer network (3) never had 2G, VoLTE is the only option currently for calls. Other networks have 2G as an option for calls once 3G is shutdown, hence EE working on the phone.