I had this error last night! The problem is with the router/nat at your customers. It is not including its IP/Domain in the header. I had to set my particular router's ALG to ignore/passthrough SIP ALG. Many routers only allow ALG on or off. You want off. But, you need to configure for NAT on your clients and FS. If your FS server is LOCAL to where you "setup extensions in FreeSwitch" there is a lot still to configure. Let me know I will tell you what I know about that. Also, what is the phone or ata brand being used? Sean -----Original Message----- From: freeswitch-users-bounces@lists.freeswitch.org [mailto:freeswitch-users-bounces@lists.freeswitch.org] On Behalf Of pratham2013 Sent: Tuesday, April 23, 2013 1:29 PM To: freeswitch-users@lists.freeswitch.org Subject: [Freeswitch-users] ERROR 404 BAD HEADER Hello, I'm facing very strange issue. I has setup extensions in FreeSwitch and I can login and make calls but on of my customer can not register with same extension and they are getting error 400 bad contact header so I could not understand how to solve this issue. Please anyone can help? Thanks Manish Khilwani -- View this message in context: http://freeswitch-users.2379917.n2.nabble.com/ERROR-404-BAD-HEADER-tp7590040 .html Sent from the freeswitch-users mailing list archive at Nabble.com. _________________________________________________________________________ Professional FreeSWITCH Consulting Services: consulting@freeswitch.org http://www.freeswitchsolutions.com FreeSWITCH-powered IP PBX: The CudaTel Communication Server http://www.cudatel.com Official FreeSWITCH Sites http://www.freeswitch.org http://wiki.freeswitch.org http://www.cluecon.com FreeSWITCH-users mailing list FreeSWITCH-users@lists.freeswitch.org http://lists.freeswitch.org/mailman/listinfo/freeswitch-users UNSUBSCRIBE:http://lists.freeswitch.org/mailman/options/freeswitch-users http://www.freeswitch.org