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Asterisk Standard Channel Variables

There are a number of variables that are defined or read by Asterisk. Here is a listing of them. More information is available in each application's help text. All these variables are in UPPER CASE only.

Variables marked with a * are builtin functions and can't be set, only read in the dialplan. Writes to such variables are silently ignored.

Variables present in Asterisk 1.8 and forward:

  • ${CDR(accountcode)} * - Account code (if specified)
  • ${BLINDTRANSFER} - The name of the channel on the other side of a blind transfer
  • ${BRIDGEPEER} - Bridged peer
  • ${BRIDGEPVTCALLID} - Bridged peer PVT call ID (SIP Call ID if a SIP call)
  • ${CALLERID(ani)} * - Caller ANI (PRI channels)
  • ${CALLERID(ani2)} * - ANI2 (Info digits) also called Originating line information or OLI
  • ${CALLERID(all)} - Caller ID
  • ${CALLERID(dnid)} * - Dialed Number Identifier
  • ${CALLERID(name)} - Caller ID Name only
  • ${CALLERID(num)} - Caller ID Number only
  • ${CALLERID(rdnis)} * - Redirected Dial Number ID Service
  • ${CALLINGANI2} * - Caller ANI2 (PRI channels)
  • ${CALLINGPRES} * - Caller ID presentation for incoming calls (PRI channels)
  • ${CALLINGTNS} * - Transit Network Selector (PRI channels)
  • ${CALLINGTON} * - Caller Type of Number (PRI channels)
  • ${CHANNEL} * - Current channel name
  • ${CONTEXT} * - Current context
  • ${DATETIME} * - Current date time in the format: DDMMYYYY-HH:MM:SS (Deprecated; use ${STRFTIME(${EPOCH},,%d%m%Y-%H:%M:%S)})
  • ${DB_RESULT} - Result value of DB_EXISTS() dial plan function
  • ${EPOCH} * - Current unix style epoch
  • ${EXTEN} * - Current extension
  • ${ENV(VAR)} - Environmental variable VAR
  • ${GOTO_ON_BLINDXFR} - Transfer to the specified context/extension/priority after a blind transfer (use ^ characters in place of | to separate context/extension/priority when setting this variable from the dialplan)
  • ${HANGUPCAUSE} * - Asterisk cause of hangup (inbound/outbound)
  • ${HINT} * - Channel hints for this extension
  • ${HINTNAME} * - Suggested Caller*ID name for this extension
  • ${INVALID_EXTEN} - The invalid called extension (used in the "i" extension)
  • ${LANGUAGE} * - Current language (Deprecated; use ${CHANNEL(language)})
  • ${LEN(VAR)} - String length of VAR (integer)
  • ${PRIORITY} * - Current priority in the dialplan
  • ${PRIREDIRECTREASON} - Reason for redirect on PRI, if a call was directed
  • ${TIMESTAMP} * - Current date time in the format: YYYYMMDD-HHMMSS (Deprecated; use ${STRFTIME(${EPOCH},,%Y%m%d-%H%M%S)})
  • ${TRANSFER_CONTEXT} - Context for transferred calls
  • ${FORWARD_CONTEXT} - Context for forwarded calls
  • ${DYNAMIC_PEERNAME} - The name of the channel on the other side when a dynamic feature is used (removed)
  • ${DYNAMIC_FEATURENAME} - The name of the last triggered dynamic feature
  • ${DYNAMIC_WHO_ACTIVATED} - Gives the channel name that activated the dynamic feature
  • ${UNIQUEID} * - Current call unique identifier
  • ${SYSTEMNAME} * - value of the systemname option of asterisk.conf
  • ${ENTITYID} * - Global Entity ID set automatically, or from asterisk.conf

Variables present in Asterisk 11 and forward:

  • ${AGIEXITONHANGUP} - set to 1 to force the behavior of a call to AGI to behave as it did in 1.4, where the AGI script would exit immediately on detecting a channel hangup
  • ${CALENDAR_SUCCESS} * - Status of the CALENDAR_WRITE function. Set to 1 if the function completed successfully; 0 otherwise.
  • ${SIP_RECVADDR} * - the address a SIP MESSAGE request was received from
  • ${VOICEMAIL_PLAYBACKSTATUS} * - Status of the VoiceMailPlayMsg application. SUCCESS if the voicemail was played back successfully, {{FAILED} otherwise