Thank you very much for the fast response. I can see a
[2020-04-21 08:17:29] WARNING[15692] res_pjsip_outbound_registration.c: No response received from ‘sip:sipconnect.ipfonie.de’ on registration attempt to ‘sip:[email protected]’, retrying in ‘300’
I am using sngrep on the asterisk an I can see that the provider is sending me back a 401. I will check tcpdump next and then the firewall, as you suggest to do. Thank you again