I am experiencing this weir issue. On some calls I don't get 200 OK and ACK and so the is dropped because INVITE expres. this is the log about 3 calls, the first ans second are without 200 OK ans ACK the tird one is with them and it is estabilished in a good way. A is the voip customers B is ser proxy C is the PSTN gateway 7331.881781 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7331.883158 B -> A SIP Status: 407 Proxy Authentication Required 7331.987931 A -> B SIP Request: ACK sip:0828963359@voip.prova.it 7331.988081 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7332.018157 B -> A SIP Status: 100 trying -- your call is important to us 7332.018602 B -> C SIP/SDP Request: INVITE sip:0828963359@C:5060, with session description 7332.114175 C -> B SIP Status: 100 Trying 7332.176249 C -> B SIP Status: 183 Session Progress 7332.177555 B -> A SIP Status: 183 Session Progress 7333.637122 C -> B SIP/SDP Status: 183 Session Progress, with session description 7333.638364 B -> A SIP/SDP Status: 183 Session Progress, with session description 7377.818129 B -> A SIP Status: 408 Request Timeout 7377.825608 B -> C SIP Request: CANCEL sip:0828963359@C:5060 7377.857091 A -> B SIP Request: ACK sip:0828963359@voip.prova.it 7377.897414 C -> B SIP Status: 200 OK 7377.898809 C -> B SIP Status: 487 Request Terminated 7377.899679 B -> C SIP Request: ACK sip:0828963359@C:5060 7394.152872 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7394.154283 B -> A SIP Status: 407 Proxy Authentication Required 7394.263174 A -> B SIP Request: ACK sip:0828963359@voip.prova.it 7394.314345 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7394.344910 B -> A SIP Status: 100 trying -- your call is important to us 7394.345321 B -> C SIP/SDP Request: INVITE sip:0828963359@C:5060, with session description 7394.439264 C -> B SIP Status: 100 Trying 7394.506851 C -> B SIP Status: 183 Session Progress 7394.508176 B -> A SIP Status: 183 Session Progress 7395.305016 C -> B SIP/SDP Status: 183 Session Progress, with session description 7395.306549 B -> A SIP/SDP Status: 183 Session Progress, with session description 7439.955201 B -> A SIP Status: 408 Request Timeout 7439.962438 B -> C SIP Request: CANCEL sip:0828963359@C:5060 7439.997963 A -> B SIP Request: ACK sip:0828963359@voip.prova.it 7440.042139 C -> B SIP Status: 200 OK 7440.046886 C -> B SIP Status: 487 Request Terminated 7440.047528 B -> C SIP Request: ACK sip:0828963359@C:5060 7460.312529 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7460.314196 B -> A SIP Status: 407 Proxy Authentication Required 7460.343504 A -> B SIP Request: ACK sip:0828963359@voip.prova.it 7460.417725 A -> B SIP/SDP Request: INVITE sip:0828963359@voip.prova.it, with session description 7460.447096 B -> A SIP Status: 100 trying -- your call is important to us 7460.447528 B -> C SIP/SDP Request: INVITE sip:0828963359@C:5060, with session description 7460.545094 C -> B SIP Status: 100 Trying 7460.613676 C -> B SIP Status: 183 Session Progress 7460.614909 B -> A SIP Status: 183 Session Progress 7461.520262 C -> B SIP/SDP Status: 183 Session Progress, with session description 7461.521608 B -> A SIP/SDP Status: 183 Session Progress, with session description 7463.544538 C -> B SIP/SDP Status: 200 OK, with session description 7463.546046 B -> A SIP/SDP Status: 200 OK, with session description 7463.586935 A -> B SIP Request: ACK sip:0828963359@C:5060 7463.595536 B -> C SIP Request: ACK sip:0828963359@C:5060 7511.516164 A -> B SIP Request: BYE sip:0828963359@C:5060 7511.532938 B -> C SIP Request: BYE sip:0828963359@C:5060 7511.606909 C -> B SIP Status: 200 OK 7511.607877 B -> A SIP Status: 200 OK Should this behavior be triggered by some misconfiguration in my ser.cfg or it is only about the PSTN gateway not sending 200 OK? Many Thnaks Rosario Rosario Pingaro D. Lgs 196/2003 Il presente messaggio contiene informazioni confidenziali, indirizzate esclusivamente alle persone sopra indicate. Se il ricevente non è tra dette persone, non dovrà intraprendere alcuna azione, tipo copia, stampa o trasmettere il suo contenuto a terzi ed i relativi allegati, ma solo informare il mittente dell'errore e cancellare il messaggio. Il mittente dovrà, altresì, accertarsi che gli allegati non contengano virus prima di aprirli.