I've been using SMARTY for a month with no problems but suddenly can't make or receive calls. I got a new SIM and data/texts is fine.
I've done a factory reset, reset phones and network and have a strong signal.
My phone is. POCO M4 Pro.
Yes, I ordered a new SIM, reset factory settings, took out the SIM and restarted the phone, reset network settings, gave customer service my phone IMEI.