Hello, I've the same deployment. And I don't have any problem,.. but in kamailio.cfg I setted the Virtual IP listen=udp:X.X.X.43:5060 At least this is the Ip that should work. I hope this help you. Regards. 2013/11/12 Nguyễn Đức Vinh &lt;vinhndk50ca(a)gmail.com <mailto:vinhndk50ca@gmail.com>> Hi all I want to setup IP failover for Kamailio: I have 2 hosts A (IP: X.X.X.32) and B (X.X.X.36), with 2 running kamailios. Using Keepalive to setup IP failover as , virtual IP *is X.X.X.43*. On host A, kamailio was binded to *listen=udp:0.0.0.0:5060 <http://0.0.0.0:5060>* and host A is MASTER with virtual IP *Problem is:* Client send REGISTER to X.X.X.43:5060. It recieved 401 respond from X.X.X.32:5060 (actual IP of A), not as expected from X.X.X.43:5060 (To check if keepalived setting OK or not, I have *nc -l 5060* on host A, and using nc X.X.X.43 5060 on client, wireshark show that responds is from X.X.X.43 -> keepalived work OK Is there any difference between *kamailio* and *nc* cause they both bind to 0.0.0.0, but repond on differ IP? Thanks Vinh Nguyen _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org <mailto:sr-users@lists.sip-router.org> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users