Hangup cause codes

The hangup_cause value appears in CDR responses and webhook payloads (pbx.call.hangup, pbx.cdr.created). Codes follow ITU-T Q.850, mapped from SIP responses by Zorio PBX.

Most common codes

hangup_cause	Meaning	Real-world scenario
NORMAL_CLEARING	Call ended normally	One of the two parties hung up after talking
NO_ANSWER	Ring timeout, nobody picked up	The customer didn't pick up or was away from the phone
USER_BUSY	Destination busy	The customer was on another call
CALL_REJECTED	Destination rejected the call	The customer pressed "decline" on their phone
ORIGINATOR_CANCEL	Agent / system cancelled before answer	The agent changed their mind and hung up while it was still ringing
RECOVERY_ON_TIMER_EXPIRE	Call hung due to SIP timeout	Network or PBX technical issue

Routing-related codes

hangup_cause	Meaning
UNALLOCATED_NUMBER	The number doesn't exist in the network (e.g. 1XX, fake prefixes)
NO_ROUTE_DESTINATION	No route to destination (e.g. trunk not configured)
NO_ROUTE_TRANSIT_NET	The trunk refused the call
DESTINATION_OUT_OF_ORDER	The destination is offline
INVALID_NUMBER_FORMAT	Bad number format (e.g. extra chars, wrong prefix)
FACILITY_REJECTED	The carrier refused the route

Call quality codes

hangup_cause	Meaning
MEDIA_TIMEOUT	RTP packets stopped arriving for N seconds (network dropped)
BEARERCAPABILITY_NOTAVAIL	Codec mismatch between the two parties
INCOMPATIBLE_DESTINATION	Different standards (e.g. analog ↔ SIP can't bridge)
EXCHANGE_ROUTING_ERROR	Carrier routing error

Policy-related codes

hangup_cause	Meaning
CALL_REJECTED	Hard reject (e.g. DNC list, blacklist)
INTERWORKING	Protocol incompatibility (e.g. ISDN ↔ SIP)
BEARERCAPABILITY_NOTAUTH	Not authorized to use this service
CHANNEL_UNACCEPTABLE	Channel not ready

Overload-related codes

hangup_cause	Meaning
NORMAL_TEMPORARY_FAILURE	Temporary failure, retry later
SWITCH_CONGESTION	Platform overloaded, can't accept more
REQUESTED_CHAN_UNAVAIL	No free channels on the trunk
RESOURCE_UNAVAILABLE	Out of resources (e.g. SBC)

Internal-system codes

hangup_cause	Meaning
LOSE_RACE	Lost the race when two calls hit the same number (only one wins)
MANAGER_REQUEST	Admin / supervisor hung up the call manually via API
SYSTEM_SHUTDOWN	System is shutting down
BLIND_TRANSFER	Call was blind-transferred to another number
ATTENDED_TRANSFER	Call was attended-transferred to another number
PICKED_OFF	Call was picked off the queue by another extension

Mapping to the result field

The result field in the CDR is a simpler classification so CRMs can aggregate easily. Mapping rules:

Condition	result
hangup_cause = NORMAL_CLEARING + billsec > 0	answered
hangup_cause = NORMAL_CLEARING + billsec = 0	no_answer (special case: agent hung up immediately after answering)
hangup_cause = NO_ANSWER	no_answer
hangup_cause = USER_BUSY	busy
hangup_cause = CALL_REJECTED	rejected
hangup_cause = ORIGINATOR_CANCEL	cancelled
Call went to voicemail	voicemail
Anything else (network, routing, system errors)	failed

When you see an unknown hangup_cause

If you see a code that isn't listed above (e.g. BIB_NA, XXX_ZZZ), it could be:

• A carrier-specific extended code (Viettel, Mobifone, ...).
• A rare infrastructure issue — report it to Zorio support with the call_uuid for tracing.

Full Q.850 reference: ITU-T Q.850.