Any provider that allows you to enter their credentials into the phone to register to their service. No idea where in the world you are but there could be thousands of providers.

Looks like Yeastar has something in their knowledgebase about it: https://support.yeastar.com/hc/en-us/articles/226529408-How-to-Add-P-Asserted-Identity-in-SIP-INVITE-Packet

Hope this helps

If you already signed up with a VoIP provider you should call them and ask how long it would take them to port and replace your number with the ported one.

Does Fonial have an API you can use to make calls? Python seems to have a Fonial SDK you can install, you just need the API key from Fonial and a valid account and it shouldn’t be too hard to make something that asks for a phone number and then the scripts calls it.

What are you logs showing when you investigate? Are calls even hitting your SBC? If they are getting to the SBC are they being forwarded to Asterisk?