Usando la Aplicación ChanIsAvail() para verificar el status de nuestros canales.

Con esta aplicación podemos verificar si uno o varios canales estan disponibles, en el siguiente dial plan verificamos al disponibilidad de  dos canales ZAP  (DAHDI).  Luego  tratara de realizar la llamada por el canal que este disponible  o de lo contrario nos  indicara que todas las lineas estan ocupadas.

ChanIsAvail()




; Check the availability of Zap/1 and Zap/2:
exten => 123,1,ChanIsAvail(Zap/1&Zap/2,j)
; As an exception, using priority jumping, because we want to announce
; something to the caller if no channel is available

; at least one channel is available - dial this channel:
exten => 123,2,NoOp(${AVAILORIGCHAN} is available)
exten => 123,3,Dial(${AVAILORIGCHAN}/123456)

; if the call goes to priority 102 landen, neither Zap/1 nor Zap/2 is av
ailable
exten => 123,102,Playback(all-channels-busy)




ChanIsAvail()

Indicates whether the specified channel is available.

        
          ChanIsAvail(technology1/resource1[&technology2/resource2...][,options])
        
      

Verifies that the one or more of the queried channels is available, in the order specified. Returns 0 on success or -1 on failure.

If the s (state) option is given, Asterisk will treat the channel as unavailable if it is in use, even if it is capable of taking another call. Option j sets priority jumping to n+101 if the channel is unavailable.

	The mere fact of a channel being available does not automatically mean that it is free for use or that the device on the channel will accept a call. That is determined using a Dial() to the channel.

ChanIsAvail() sets the following channel variables:

${AVAILCHAN}

The name of the accessible channel, including the session number of the call.

${AVAILORIGCHAN}

The canonical channel name (i.e., the channel name without session number).

${AVAILSTATUS}

Status code of the channel:

AST_DEVICE_UNKNOWN (0)

Status of the channel is unknown. It is a valid channel, but we don't know about its state.

AST_DEVICE_NOT_INUSE (1)

The channel is not in use.

AST_DEVICE_IN_USE (2)

The channel is in use.

AST_DEVICE_BUSY (3)

The channel is busy.

AST_DEVICE_INVALID (4)

The channel is unknown.

AST_DEVICE_UNAVAILABLE (5)

The channel is not available and not registered.

AST_DEVICE_RINGING (6)

The channel is ringing.

	This application does not behave as expected on MGCP channels.