There are many ways to skin a cat… You could use something like
There is a lot of information about DIY stuff out there but the cyberlink solution listed “just works” and I believe it comes with some perks in the way of commercial modules.
I just read on here by someone being frustrated by call quality with CyberLynk and wanting other options. I’ll keep looking or seek more input. Thanks.
If you keep googling there are options for Digital Ocean or Vultr as well.
Or you could try and roll your own.
For SIP providers, again plenty of choices. Sangoma has their own caleld SIPStation, there is Vitelity, there is Twilio and many others. Not sure that you could go wrong with any of them.