Hello, my FS has a trunk with an openser: FS -> openser (sip.test.com - 1.2.3.4) -> cisco gateway I have configured a gateway with this sip proxy / realm and I have a problem with BYE. When I call from PSTN (cisco gateway) to FS, the cisco device set a realm "1.2.3.4" and openser ask for authentication, while FS tell: 2012-06-14 14:23:44.018150 [ERR] sofia_reg.c:2160 Cannot locate any authentication credentials to complete an authentication request for realm '"1.2.3.4"' I know that FS asks that realm configured in the gateway section (sip.test.com) should match the realm in the challenge packet from the other device (that instead is 1.2.3.4), but the Reverse DNS of 1.2.3.4 is sip.test.com (and viceversa). Should FS respond to the challenge packet? How can I solve this problem? Best Regards,