Hello Use two Asterisk servers. I registered Server2 in Server1. When I bind for an extension in the Server1, the hard call some as and is interrupted. My configuration: iax.conf / Server 1 [20001] type=friend accountcode=20001 host=dynamic secret=secret context=sip disallow=all allow=gsm auth=plaintext ////////////////////////////////////////////////////// iax.conf / Server 2 register => 20001:secret@ipserver1 [20001] type=user context=fromiax auth=plaintext Extension / Server2 exten => _33.,1,SetCallerId,${CALLERIDNUM} exten => _33.,2,Dial(IAX2/20001:secret@ipserver1/${EXTEN:2}) exten => _33.,3,Congestion Error -- Executing Dial("IAX2[40002@40002]/17", "IAX2/20001:secret@ipserver1/123456") in new stack -- Called 20001:secret@ipserver1/123456 -- Call accepted by 24.232.89.22 (format GSM) -- Format for call is GSM -- Operating with different codecs, can't native bridge... -- Hungup == Spawn extension (sip, 33123456, 2) exited non-zero on 'IAX2[40002@40002]/17' -- Hungup 'IAX2[40002@40002]/17' Necessary of aid. It forgives my English. Thanks Tiago