Hi, I have been testing 'DNS SRV', backup server and t_replicate with two 'ser'servers, BT101(firmware:1.0.7.11), and two GXP2000s(1.0.1.9). The t_replicate works fine between sip1(main) and sip2(backup) servers. Then, I stopped 'ser' on sip1 server, three UAs sent REGISTERs not to sip1 but to sip2. I tested make calls between three UAs, sip2 took care of sip calls, worked fine. After that, I restarted 'ser' on sip1. But the three UAs still send REGISTER to sip2, eventhough sip1 came back and became alive. I set up 5 minutes intervals for these theree UAs for REGISTER. So, I stopped 'ser' on sip2 for 10-15 minutes, three UAs sent REGISTERs to sip1 again and tryed to 't_replicate' to sip2, these were failed as 'destination unreachable'. Then I restarted 'ser' on sip2 again. After REGISTERed on sip1, t_replicate send REGISTERs from sip1 to sip2. Now, everything works fine. Is this server side opration normal? Or these UAs are still bad boys? Regards, Zen