Hello, start with the usual topics, e.g. looking to some SIP traces with ngrep or sngrep and get more information why the calls are failing. If you have more information, ask again sharing that information on the list to get more specific answers can also help. 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 Anh Cao Sent: Tuesday, May 24, 2022 8:45 AM To: sr-users(a)lists.kamailio.org Subject: Re: [SR-Users] Load balancer and consult transfer Hi all, Could anyone help me please ... On Tue, May 17, 2022, 11:19 Anh Cao <anhright@gmail.com<mailto:anhright@gmail.com>> wrote: Hi all, I'm building an simple PBX with 1 Kamailio as load balancer for several Asterisk servers. My issue is if an extension is in-call on Asterisk#1 wants to consult transfer to another number, it makes another call and Kamailio forward this new call to another Asterisk and cause call tranfer will fail. Does anyone here have tips or sugestions to resolve this? Thanks in advance for your help. Best regards