I have Sprint now but, considering the SIM. Not sure for sure but definitely looking into the possibility. Sometimes I travel up to the mountains and highly rely on wifi calling because there is no native signal there for either Sprint Verizon or T-Mobile. Both Verizon and Sprint wrote when I local carrier so we get service. The only one with Native service up there is AT&T but it seemed to be pretty spotty last time I checked but it does work. So up there use mostly WiFi calling which I love to use MiFi calling anyway so my question is does mint Sim use Wifi calling. I figure if I'm home and there's a Wi-Fi connection why should I use up space and capacity on the tower when I can use my wifi connection. Right now I use about 800 minutes on mobile in about $2,000 a month on wifi calling so WiFi calling is very important to me. I would not want to use 3000 minutes on T-Mobile network plus two thousand texts plus 1 GB of data all over their Network and I can use Wifi calling especially when I only paying 11 bucks a month. Any help here.