I still have SMS tied to Hangouts. I moved my phone number to Google Voice when I left the US years ago and kept it on there when I moved back. It's been migrat

I still have SMS tied to Hangouts. I moved my phone number to Google Voice when I left the US years ago and kept it on there when I moved back. It's been migrated to hangouts, which is pretty much total garbage now. I want to migrate my phone number to another service, but I also want to get off Android entirely at some point and want to find a service with a public API so I can eventually write Plasma Apps or a Matrix bridge. Are there any good VoIP providers I can pay for monthly that fit that bill?