@a2es@mstdn.social Thanks for the hint. I already had looked at pjsua, but found it too complicated to build.

Yesterday I came across it again looking at #alpine (base to the #ntfy docker image) for #sip software. In Alpine it is easy to install, but I couldn't get it to make a call using #1und1.de in a quick test.

I'll need to look at a working connection again to find the differences in the sip traces.

Once installed pjsua is like baresip a really nice client.