Problemas al integrar Asterisk con CCM

Estoy tratando de integrar el CCM con Asterisk, ya hice todas las configuraciones pero el momento de llamar desde el Asterisk hacia las extensiones del callmanager me da este error.

Oct 8 09:57:25] VERBOSE[28822] logger.c: – Executing [708@default:1] Macro(“SIP/600-08661388”, “dialout-callmanager|708”) in new stack
[Oct 8 09:57:25] VERBOSE[28822] logger.c: – Executing [s@macro-dialout-callmanager:1] ChanIsAvail(“SIP/600-08661388”, “SIP/callman01”) in new stack
[Oct 8 09:57:25] DEBUG[28822] app_macro.c: Executed application: ChanIsAvail
[Oct 8 09:57:25] VERBOSE[28822] logger.c: – Executing [s@macro-dialout-callmanager:2] Set(“SIP/600-08661388”, “AVAILCHAN=SIP/callman01”) in new stack
[Oct 8 09:57:25] DEBUG[28822] app_macro.c: Executed application: Set
[Oct 8 09:57:25] VERBOSE[28822] logger.c: – Executing [s@macro-dialout-callmanager:3] Dial(“SIP/600-08661388”, “SIP/callman01/708”) in new stack
[Oct 8 09:57:25] VERBOSE[28822] logger.c: – Called callman01/708
[Oct 8 09:57:25] VERBOSE[28822] logger.c: – SIP/callman01-08671aa8 is ringing
[Oct 8 09:57:27] VERBOSE[26397] logger.c: – Got SIP response 503 “Service Unavailable” back from 131.150.25.100
[Oct 8 09:57:27] VERBOSE[28822] logger.c: – SIP/callman01-08671aa8 is circuit-busy
[Oct 8 09:57:27] VERBOSE[28822] logger.c: == Everyone is busy/congested at this time (1:0/1/0)
[Oct 8 09:57:27] DEBUG[28822] app_macro.c: Executed application: Dial
[Oct 8 09:57:27] VERBOSE[28822] logger.c: – Executing [s@macro-dialout-callmanager:4] Hangup(“SIP/600-08661388”, “”) in new stack
Timbra pero no se conecta la llamada y no tengo idea que esta mal.
Si estoy configurando mal el asterisk o el CCM

“Service Unavailable”, from CCM, typically means that you haven’t configured a trunk, in CCM, to match the IP address of Asterisk. Unfortunately, I haven’t done the CCM side of configuring a trunk. Our Asterisk configuration for CCM is trivial, and it will even work with SIP/255.255.255.255/.

So, probably, “estoy configurando mal el CCM”