Hi Badri, It can happen if you use sipp and you place calls (sending REGISTER before each INVITE) with the same username.I found out that passing "-cid_str somestring-%u-%s" to sipp helps. Regards,Dragos From: Daniel-Constantin Mierla <miconda(a)gmail.com> To: Kamailio (SER) - Users Mailing List <sr-users(a)lists.sip-router.org> Sent: Friday, April 3, 2015 11:53 AM Subject: Re: [SR-Users] Reg. invalid cseq error. Hello, does it happen to have a sample trace of the register and the reply? The reason can be that the register request has a lower cseq that another register processed before. Cheers, Daniel On 02/04/15 17:00, Badri Ranganathan wrote: -- Daniel-Constantin Mierla http://twitter.com/#!/miconda - http://www.linkedin.com/in/miconda Kamailio World Conference, May 27-29, 2015 Berlin, Germany - http://www.kamailioworld.com _______________________________________________ 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