Any VoIP provider, I suppose. I have a few phone numbers at voip.ms, have a VoIP phone on my desk, and selectively forward the numbers to my cell phone. Outboun

Any VoIP provider, I suppose. I have a few phone numbers at voip.ms, have a VoIP phone on my desk, and selectively forward the numbers to my cell phone. Outbound calls from a cellphone using such a number is a bit more awkward, requiring either a SIP app or calling into the system before punching in the number to dial. (Maybe there are apps to simplify this by now?) SMS is even more awkward, though there are some APIs.