Dear, Following the configuration available on the TM Modules documentation. Src : https://www.kamailio.org/docs/modules/devel/modules/tm.html#tm.serial_forki… request_route { request_route{ $var(uri1)="sip:9919995@192.168.1.41"; > $var(uri2)="sip:9919992@192.168.1.41"; > $var(uri3)="sip:9919991@192.168.1.41"; > $var(uri4)="sip:9919994@192.168.1.41"; > append_branch ("$var(uri1"); > append_branch ("$var(uri2"); > append_branch ("$var(uri3"); > append_branct_("$var(uri4"); t_relay(); > break; } The server send INVITE to himself. Fixing the problem : request_route{ $var(uri1)="sip:9919995@192.168.1.41"; > $var(uri2)="sip:9919992@192.168.1.41"; > $var(uri3)="sip:9919991@192.168.1.41"; > $var(uri4)="sip:9919994@192.168.1.41"; > lookup("location","$var(uri4)"); > append_branch(); > lookup("location","$var(uri1)"); > append_branch(); > lookup("location","$var(uri2)"); > append_branch(); > lookup("location","$var(uri3)"); t_relay(); > break; > } Is this the correct way ? Best regards. Thomas <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmailVirus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2