My goal is to perform a call using VoIP and play an audio file (no matter what format) with Python and record the call. I found some libraries but their documentation is unclear and they don't seem to be maintained. I have also tried using external utilities like sipcli. This worked but I want to have more control over calling and I'd like not to depend on external software.
P.S. I need it to both work on Linux and on Windows
Have you explored Pjsip python module.
https://www.pjsip.org/python/pjsua.htm
python example:
https://svn.pjsip.org/repos/pjproject/trunk/pjsip-apps/src/python/samples/call.py