I'm using Mint mobile (MVNO that uses T-Mobile network) and I have problems with dropped calls due to poor signal in part of my home. The big problem I have is WiFi calling works intermittently, the phone is automatically changing my WiFi preferences to prefer mobile network, and then the other major issue I'm having is texting....messages fail to send but the recipient gets the same message multiple times....or the message says it was sent and the recipient never received it.
I posted a thread about my disappointment with this device. I have pre-ordered the Pixel 4 XL today and will be getting rid of this device. Its useless if it can't perform basic functions expected of a phone....especially one at this price point.