Hi, When client send register message that reg-id in contact is "0", kamailio failed to update contacts info， but it will send 200-register to client, this will cause one issue that no one can find this client(will always be 404 error) reg-id in message: Contact: <sip:2015@100080:5060;ob>;reg-id=0 Related logs: /usr/local/sbin/kamailio[30325]: ERROR: registrar [savec:402]: pack_ci(): invalid reg-id value /usr/local/sbin/kamailio[30325]: ERROR: registrar [savec:685]: update_contacts(): failed to pack contact specific info I think registrar should reply 4xx message when reg-id's value is 0 Best Regards, Shengy --- Reply to this email directly or view it on GitHub: https://github.com/kamailio/kamailio/issues/497