Hi! I have an issue with no ringback or audio that has just started in the last few weeks. No changes in FS, which has been rock solid for a long time. I think my voip provider Pennytel has upgraded or changed their servers. Anyway, the difference in signalling is as follows: This does not work: INVITE sip:number@sip.pennytel.com SIP/2.0 SIP/2.0 100 Trying SIP/2.0 401 Unauthorized ACK sip:number@sip.pennytel.com SIP/2.0 INVITE sip:number@sip.pennytel.com SIP/2.0 SIP/2.0 100 Trying SIP/2.0 183 Session Progress SIP/2.0 180 Ringing SIP/2.0 200 OK ACK sip:202.85.243.105:5061 SIP/2.0 BYE sip:202.85.243.105:5061 SIP/2.0 SIP/2.0 200 OK This works INVITE sip:number@sip.pennytel.com SIP/2.0 SIP/2.0 100 Trying SIP/2.0 401 Unauthorized ACK sip:number@sip.pennytel.com SIP/2.0 INVITE sip:number@sip.pennytel.com SIP/2.0 SIP/2.0 100 Trying SIP/2.0 183 Session Progress SIP/2.0 200 OK ACK sip:202.85.243.105:5061 SIP/2.0 And I see after the Ringing signal in the case that does not work (there is no ringing signal in the case that does work): 2011-03-21 20:28:25.677621 [DEBUG] sofia.c:4641 Channel sofia/external/0393011079 skipping state [proceeding][180] received after a RINGING Can anyone point me to a reason for the difference in signalling and what I can do to get audio 100% of the time? THanks