You can open up the phone and modify the ESP32. I do that pretty often with IoT devices. It's not as easy as setting a URL, but totally possible if you are determined enough.
I'm going to politely weigh in here and say things Sean won't say about himself.
You're talking to someone who has spent the last ten years building open source WebRTC software that many, many, many people use and that he's never tried to commercialize. He works tirelessly to make the Pion community welcoming to everyone, from engineers with a ton of networking/video experience to brand new contributors. He wrote the guide that should be everyone's first read about WebRTC.[] All of it as a labor of love.
This wasn’t built to be a general purpose phone. It’s a single purpose tool, if it had full SIP support it would need more expensive hardware. When I worked on this I knew I wasn’t building some interoperable general tool.
I am being honest with you. For me the ‘hacker spirit’ means cracking things open and learning how they work. So I totally encourage others to do it.
I would be perfectly fine with taking "in theory yes but actually no" (which is basically what you are saying) as the answer instead of this roundabout way of phrasing it. I appreciate what you did, but this discussion is kind of unnecessary.
You can open up the phone and modify the ESP32. I do that pretty often with IoT devices. It's not as easy as setting a URL, but totally possible if you are determined enough.