The Asterisk hangup causes are delivered to the dialplan in the ${HANGUPCAUSE} channel variable after a call (after execution of "dial").

In SIP, we have a conversion table to convert between SIP return codes and Q.931 both ways. This is to improve SIP/ISDN compatibility.

These are the current codes, based on the Q.850/Q.931 specification:

AST_CAUSE_UNALLOCATED 1
AST_CAUSE_NO_ROUTE_TRANSIT_NET 2
AST_CAUSE_NO_ROUTE_DESTINATION 3
AST_CAUSE_MISDIALLED_TRUNK_PREFIX 5
AST_CAUSE_CHANNEL_UNACCEPTABLE 6
AST_CAUSE_CALL_AWARDED_DELIVERED 7
AST_CAUSE_PRE_EMPTED 8
AST_CAUSE_NUMBER_PORTED_NOT_HERE 14
AST_CAUSE_NORMAL_CLEARING 16
AST_CAUSE_USER_BUSY 17
AST_CAUSE_NO_USER_RESPONSE 18
AST_CAUSE_NO_ANSWER 19
AST_CAUSE_CALL_REJECTED 21
AST_CAUSE_NUMBER_CHANGED 22
AST_CAUSE_REDIRECTED_TO_NEW_DESTINATION 23
AST_CAUSE_ANSWERED_ELSEWHERE 26
AST_CAUSE_DESTINATION_OUT_OF_ORDER 27
AST_CAUSE_INVALID_NUMBER_FORMAT 28
AST_CAUSE_FACILITY_REJECTED 29
AST_CAUSE_RESPONSE_TO_STATUS_ENQUIRY 30
AST_CAUSE_NORMAL_UNSPECIFIED 31
AST_CAUSE_NORMAL_CIRCUIT_CONGESTION 34
AST_CAUSE_NETWORK_OUT_OF_ORDER 38
AST_CAUSE_NORMAL_TEMPORARY_FAILURE 41
AST_CAUSE_SWITCH_CONGESTION 42
AST_CAUSE_ACCESS_INFO_DISCARDED 43
AST_CAUSE_REQUESTED_CHAN_UNAVAIL 44
AST_CAUSE_FACILITY_NOT_SUBSCRIBED 50
AST_CAUSE_OUTGOING_CALL_BARRED 52
AST_CAUSE_INCOMING_CALL_BARRED 54
AST_CAUSE_BEARERCAPABILITY_NOTAUTH 57
AST_CAUSE_BEARERCAPABILITY_NOTAVAIL 58
AST_CAUSE_BEARERCAPABILITY_NOTIMPL 65
AST_CAUSE_CHAN_NOT_IMPLEMENTED 66
AST_CAUSE_FACILITY_NOT_IMPLEMENTED 69
AST_CAUSE_INVALID_CALL_REFERENCE 81
AST_CAUSE_INCOMPATIBLE_DESTINATION 88
AST_CAUSE_INVALID_MSG_UNSPECIFIED 95
AST_CAUSE_MANDATORY_IE_MISSING 96
AST_CAUSE_MESSAGE_TYPE_NONEXIST 97
AST_CAUSE_WRONG_MESSAGE 98
AST_CAUSE_IE_NONEXIST 99
AST_CAUSE_INVALID_IE_CONTENTS 100
AST_CAUSE_WRONG_CALL_STATE 101
AST_CAUSE_RECOVERY_ON_TIMER_EXPIRE 102
AST_CAUSE_MANDATORY_IE_LENGTH_ERROR 103
AST_CAUSE_PROTOCOL_ERROR 111
AST_CAUSE_INTERWORKING 127

For more information:

app_dial.c