Really, I was talking about VoIP, but being integrated into the native calling app as a configurable option where you could just plugin details of your SIP prov

Really, I was talking about VoIP, but being integrated into the native calling app as a configurable option where you could just plugin details of your SIP provider or something like that. Presumably that would be done over LTE, but would be essentially obscured from your phone plan provider for privacy sake.