Abaixo segue os arquivos utilizados nos testes:
# vi /etc/asterisk/extensions.conf
[TR001]
include => default
[TR002]
include => default
[TR003]
include => default
[TR004]
include => default
[analogico]
include => default
[default]
include => ramais
include => 141_Digital
include => Impacta
include => ligacoes_cel_local
include => ligacoes_cel_DDD
include => locais
include => ligacoes_DDD
include => ligacoes_DDI
include => entrante_analogico
[ramais]
exten => _6XXX,1,dial(sip/${EXTEN})
exten => _6XXX.,n,Congestion(10)
exten => _6XXX.,n,Hangup
[141_Digital]
exten => _2121XXXX,1,Dial(Dahdi/g1/${EXTEN:4},60)
exten => _2121XXXX.,n,Congestion(10)
exten => _2121XXXX.,n,Hangup()
[Impacta]
exten => _2123XXXX,1,Dial(Dahdi/g4/${EXTEN:4},60)
exten => _2123XXXX.,n,Congestion(10)
exten => _2123XXXX.,n,Hangup()
[locais]
exten => _X.,1,Dial(sip/operadora_voip/${EXTEN},60)
exten => _X.,n,Congestion(10)
exten => _X.,n,Hangup()
[ligacoes_DDD]
exten => _0X.,1,Dial(sip/operadora_voip/${EXTEN},60)
exten => _0X.,n,Congestion(10)
exten => _0X.,n,Hangup()
[ligacoes_DDI]
exten => _00X.,1,Dial(sip/operadora_voip/${EXTEN},60)
exten => _00X.,n,Congestion(10)
exten => _00X.,n,Hangup()
[ligacoes_cel_local]
exten => _[7-9].,1,Dial(Dahdi/g5/${EXTEN},60)
exten => _[7-9].,n,Congestion(10)
exten => _[7-9].,n,Hangup()
[ligacoes_cel_DDD]
exten => _0XXXX[7-9].,1,Dial(Dahdi/g5/041${EXTEN:3},60)
exten => _0XXXX[7-9].,n,Congestion(10)
exten => _0XXXX[7-9].,n,Hangup()
[entrante_analogico]
exten => s,1,Dial(Dahdi/g1/2000,60)
exten => s,n,Congestion(10)
exten => s,n,Hangup()
# vi /etc/asterisk/sip.conf
[general]
allowguest=no
bindaddr=0.0.0.0
srvlookup=yes
disallow=all
allow=alaw
allow=ulaw
allow=g726
allow=gsm
allow=ilbc
tos=0x18
language=pt_BR
videosupport=yes
nat=yes
bindport=5060
[6000]
type=friend
context=default
secret=6000
host=dynamic
port=5060
callerid="6000" <6000>
call-limit=10
fromuser=
fromdomain=
dtmfmode=auto
disallow=all
allow=alaw
allow=ulaw
callgroup=
pickupgroup=
qualify=no
canreinvite=no
Atenção: Por algum motivo, que não sei explicar, ao reiniciar a máquina o dahdi não sobe correto, ocorre falha. Para corrigir, tem que parar o asterisk e o dahdi e depois iniciar o dahdi e o asterisk. Abaixo o script 'AjusteFinal.sh' que tenho no arquivo '/etc/rc.local':
# vi /etc/AjusteFinal.sh
#!/bin/sh
#
# This script will be executed *after* all the other init scripts.
# You can put your own initialization stuff in here if you don't
# want to do the full Sys V style init stuff.
touch /var/lock/subsys/local
/etc/AjusteFinal.sh
Pronto! Só iniciar os testes.
Referências: