Hello, check if the call-id value is not somehow changed by the endpoints, then also direction has to be detected properly (check from/to/rr tags). Cheers, Daniel On 23.03.22 16:05, Marrold wrote: Hi, I have enabled the TOPOH module with mask_callid enabled, but it's generating a new Call-ID for a BYE which gets rejected with a 481 downstream. If I disable the TOPOH module it works as expected. Does anyone know where I should start looking? SIP-wise the initial BYE seems compliant. This is Kamailio 5.5.3 on Debian 11 Thanks Matthew __________________________________________________________ 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 -- Daniel-Constantin Mierla -- www.asipto.comwww.twitter.com/miconda -- www.linkedin.com/in/miconda Kamailio Advanced Training - Online March 28-31, 2022 (Europe Timezone) * https://www.asipto.com/sw/kamailio-advanced-training-online/ __________________________________________________________ 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