You can find explanations of the full ISDN Q.850 cause codes:
ISDN Cause Codes:
| No: | Explanation |
| 0 | Valid cause code not yet received |
| 1 | Unallocated (unassigned) number |
| 2 | No route to specified transit network |
| 3 | No route to destination |
| 4 | send special information tone |
| 5 | Misdialled trunk prefix |
| 6 | Channel Unacceptable |
| 7 | Call awarded and being delivered in an established channel |
| 8 | Prefix 0 dialed but not allowed |
| 9 | Prefix 1 dialed but not allowed |
| 10 | Prefix 1 dialed but not required |
| 11 | More digits received than allowed, call is proceeding |
| 16 | Normal call clearing |
| 17 | User busy |
| 18 | No user responding |
| 19 | No answer from user (user alerted) |
| 20 | Subscriber absent |
| 21 | Call Rejected |
| 22 | Number changed |
| 23 | Redirection to new destination |
| 24 | Call suspended |
| 25 | Call resumed |
| 26 | Non selected user clearing |
| 27 | Destination out of order |
| 28 | Invalid number format |
| 29 | Facility rejected |
| 30 | Response to status enquiry |
| 31 | Normal, unspecified |
| 33 | Circuit out of order |
| 34 | No circuit/channel available |
| 35 | Destination unattainable |
| 37 | Degraded service |
| 38 | Network out of order |
| 39 | Transit delay range cannot be achieved |
| 40 | Throughput range cannot be achieved |
| 41 | Temporary failure |
| 42 | Switching equipment congestion |
| 43 | Access information discarded |
| 44 | Requested circuit/channel not available |
| 45 | Pre-empted |
| 46 | Precedence call blocked |
| 47 | Resources unavailable, unspecified |
| 49 | Quality of service unavailable |
| 50 | Requested facility not subscribed |
| 51 | Reverse charging not allowed |
| 52 | Outgoing calls barred |
| 53 | Outgoing calls barred within CUG |
| 54 | Incoming calls barred |
| 55 | Incoming calls barred within CUG |
| 56 | Call waiting not subscribed |
| 57 | Bearer capability not authorized |
| 58 | Bearer capability not presently available |
| 62 | Inconsistency in outgoing information element |
| 63 | Service or option not available, unspecified |
| 65 | Bearer capability not implemented |
| 66 | Channel type not implemented |
| 67 | Transit network selection not implemented |
| 68 | Message not implemented |
| 69 | Requested facility not implemented |
| 70 | Only restricted digital information bearer capability is available |
| 79 | Service or option not implemented, unspecified |
| 81 | Invalid call reference value |
| 82 | Identified channel does not exist |
| 83 | A suspended call exists, but this call identity does not |
| 84 | Call identity in use |
| 85 | No call suspended |
| 86 | Call having the requested call identity has been cleared |
| 87 | User not member of CUG |
| 88 | Incompatible destination |
| 89 | Non-existent abbreviated address entry |
| 90 | Destination address missing, and direct call not subscribed |
| 91 | Invalid transit network selection |
| 92 | Invalid facility parameter |
| 93 | Mandatory information element is missing |
| 95 | Invalid message, unspecified |
| 96 | Mandatory information element is missing |
| 97 | Message type nonexistent or not implemented |
| 98 | Message not compatible with call state or message type nonexistent or not implemented |
| 99 | Information element nonexistent or not implemented |
| 100 | Invalid information element contents |
| 101 | Message not compatible with call state |
| 102 | Recovery on timer expiry |
| 103 | Parameter non-existent or not implemented – passed on |
| 110 | Message with unrecognized parameter discarded |
| 111 | Protocol error, unspecified |
| 127 | Interworking, unspecified |