Contar y Limitar la cantidad de llamadas en Asterisk

Supongamos que tenemos una T1 o Troncal SIP con una cantidad de  24 canales y a l vez tenemos 6 DID. Podemos  asignar  4 canales a cada DID  para así evitar que un solo  DID consuma todos nuestros canales  y exista un balanceo.


El Siguiente ejemplo limita la cantidad de canales en el contexto count a solo 2. 

[count]
exten =>_57,1,Noop(Received call to extension ${EXTEN})

exten =>_57,n,Set(GROUP()=${CONTEXT})) ;Creamos el grupo

exten =>_57,n,GotoIf($[ ${GROUP_COUNT()} >2]?maxreached) ; verificamos


exten =>_57,n,Set(MYTRUNK=voipms)

exten=>_57,n,Dial(SIP/4443@${MYTRUNK},30)


exten=>_57,n(maxreached),Playback(all-outgoing-lines-unavailable)

exten=>_57,n(maxreached),Playback(pls-try-call-later)

exten=>_57,n,Hangup()


Under asterisk, from your dialplan or an agi script you canput your calls (that has the same purpose)
in the same group.
This can be done using the GROUP* functions under asterisk.
- With GROUP() you can retrieve or set a group for the current channel
- With GROUP_COUNT() you can retrieve the total of live channel in that group
- With GROUP_LIST, you will get a list of group where the current channel is. So you can set put the same channel in multiple group to classify them.
- With GROUP_MATCH_COUNT, you can retrieve the number of live channels in that group matching the specifed regular expression.