Thank you for hints. Daniel, using the 'path' with address of Kamailio-B in the 401 is not useful?  Regards,Hossein On Tuesday, July 13, 2021, 12:04:29 AM PDT, Daniel-Constantin Mierla &lt;miconda(a)gmail.com&gt; wrote: If I understood the scenario, the Path header is not useful -- that's for the case when there is a proxy between UA and registrar server. In this scenario seems to be the UA using alternate registrars, either by DNS or configuration. A solution is this case is to sync the two Kamailios A and B, so they accept the auth challenges generated by the other one. See:   *https://www.kamailio.org/docs/modules/stable/modules/auth.html#auth.p.secret Cheers, Daniel On 13.07.21 07:56, Alex Balashov wrote: Path header == Record-Route for REGISTERs. — Sent from mobile, with due apologies for brevity and errors. On Jul 13, 2021, at 1:22 AM, H Yavari &lt;hyavari(a)rocketmail.com&gt; wrote:  Hi to all, In a scenario, we need to change the destination of users' registration requests when they send the first 'Register' to Kamailio-A and it replies 401 to the user, next time the user sends 'Register' to Kamailio-B. User------Register-------> Kamailio-A User<-----401--------------Kamailio-A User-------Register--------> Kamailio-B RFC says we can't use the Record-Route for register because it doesn't create a dialog. Is there any option, header that Kamailio-A puts in the 401, and after that users send register to the Kamailio-B? Thank you. BR, Hossein __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions  * sr-users(a)lists.kamailio.org Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe:  * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users __________________________________________________________Kamailio - Users Mailing List - Non Commercial Discussions * sr-users(a)lists.kamailio.orgImportant: keep the mailing list in the recipients, do not reply only to the sender!Edit mailing list options or unsubscribe: * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users -- Daniel-Constantin Mierla -- www.asipto.com www.twitter.com/miconda -- www.linkedin.com/in/miconda __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions   * sr-users(a)lists.kamailio.org Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe:   * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users