I've been researching getting a mobile "phone" that is only ever used as a hotspot for an iPod touch which runs (1) an always-on VPN and (2) apps for SMS and Vo

I've been researching getting a mobile "phone" that is only ever used as a hotspot for an iPod touch which runs (1) an always-on VPN and (2) apps for SMS and VoIP voice calls. So in a way, phone that can't do voice calls sounds like a good thing to me.