(resent - as Benny is back, so it don't get lost :-) Hi! I have a problem with TCP and IPv6. Although I created transport with pjsua_transport_create(PJSIP_TRANSPORT_TCP6, ...); pjsip binds to IPv4: tcplis:5060 SIP TCP listener ready for incoming connections at 10.10.0.51:5060 pjsua_acc.c Account sip:klaus.darilion at sip.labs.nic.at added with id 0 pjsua_acc.c Unable to generate suitable Contact header for registration: Unknown error 171060 [status=171060] pjsua_acc.c Unable to create registration: Unknown error 171060 [status=171060] btw: In pjsua, IPv6 for TCP is missing completely. regards Klaus