I have a local area network with: · A Windows PC with a VOIP application · A Linux PC with KAMailIO There is also a remote Windows PC with the same VOIP application. There is also an IPhone VOIP application that communicates with the Windows PC application. All communications use the same KAMailIO system. The IPhone application communicates with the PC on the local network. It times out trying to communicate. I have tried a URL and a static IP address for SIP_DOMAIN, neither succeeds. Here are some extracts from the log (ignore timestamp gap, several calls were attempted). I think the problem is that the reply to the PC is being sent to 192.168.1.12 instead of 92.13.147.87. Mar 4 00:28:51 SIS-Server kamailio[18136]: DEBUG: <core> [ip_addr.c:243]: print_ip(): tcpconn_new: new tcp connection: 92.13.147.87 Mar 4 00:28:52 SIS-Server kamailio[18130]: DEBUG: tls [tls_server.c:354]: tls_accept(): TLS accept successful Mar 4 00:28:52 SIS-Server kamailio[18130]: DEBUG: tls [tls_server.c:361]: tls_accept(): tls_accept: new connection from 92.13.147.87:49302 using TLSv1/SSLv3 AES256-SHA 256 Mar 4 00:28:52 SIS-Server kamailio[18130]: DEBUG: tls [tls_server.c:364]: tls_accept(): tls_accept: local socket: 96.81.57.12:5061 Mar 4 00:28:52 SIS-Server kamailio[18130]: DEBUG: auth [api.c:86]: pre_auth(): auth:pre_auth: Credentials with realm '96.81.57.12' not found Mar 4 00:28:55 SIS-Server kamailio[18130]: DEBUG: registrar [reply.c:374]: build_contact(): created Contact HF: Contact: <sip:hvs_uk_pc@192.168.1.12:49302;transport=TLS;line=b3d07204a26e36e>;expires=120 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==9 && [96.81.57.12] == [127.0.0.1] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==13 && [96.81.57.12] == [192.168.1.181] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==11 && [96.81.57.12] == [96.81.57.12] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==9 && [96.81.57.12] == [127.0.0.1] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==13 && [96.81.57.12] == [192.168.1.181] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060 Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:583]: grep_sock_info(): grep_sock_info - checking if host==us: 11==11 && [96.81.57.12] == [96.81.57.12] Mar 4 00:37:09 SIS-Server kamailio[18135]: DEBUG: <core> [socket_info.c:587]: grep_sock_info(): grep_sock_info - checking if port 5060 (advertise 0) matches port 5060Mar 4 00:37:12 SIS-Server kamailio[18136]: ERROR: <core> [tcp_main.c:4159]: handle_tcpconn_ev(): connect 192.168.1.12:49302 failed Changes to KAMCTLRC are: SIP_DOMAIN=ed-todd-randd.com DBENGINE=MYSQL DBNAME=kamailio DBRWUSER="kamailio" DBRWPW="kamailiorw" Changes to KAMAILIO.CFG are: #!define WITH_MYSQL #!define WITH_AUTH #!define WITH_USRLOCDB #!define WITH_TLS Plus I set debug=4 for logging. Whatsmyip.org shows the right IP address (static) and hostname www.ed-todd-randd.com So, any clues?