Hello, not sure if I fully understand the problem. But regarding another user is registered with the same IP address as a previous user, there are several mitigations. To give two options: you could choose a really short re-registration time, you could use TCP and when you lose the connection you delete the contact. Cheers, Henning -- Henning Westerholt – https://skalatan.de/blog/ Kamailio services – https://gilawa.com<https://gilawa.com/> From: sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; On Behalf Of ??? Sent: Wednesday, November 30, 2022 2:57 AM To: sr-users(a)lists.kamailio.org Subject: [SR-Users] uac_req_send() multi-process synchronization problem When I use uac_req_send() to send a MESSAGE to the client. Will the following occur? The result of the message sent to user A is that B has received it. From the logs, the address of user A in the location table is the same as the IP address and port of user B, and the information of user A in the location table is not deleted in time. I took the address of user A directly from the location table without using KSR.registrar.reg_fetch_contacts(). If I use KSR.registrar.reg_fetch_contacts() can this be avoided. This is a multi-process synchronization problem, after user A registers, the IP port information in the address is 172.16.22.222:12345, and then user A disconnects the link because of some abnormal conditions, but it is not normal to cancel the registration, the socket link has failed, but it has not had time to delete the location, at this time user B registers, whether will it get the same IP port information as user A 172.16.22.222 : 12345, if possible? User A's location still exists, Using KSR.registrar.reg_fetch_contacts() TO query user A's location, and then using uac_req_send() to send a message to user A, User B will receive the MESSAGE. Whether this problem occurs? 从 Windows 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>发送