- 1 - Unallocated (unassigned) number
- 2 - No route to specified transit network
- 3 - No route to destination
- 6 - Channel Unacceptable
- 7 - Call awarded and being delivered in an established channel
- 16 - Normal call clearing
- 17 - User busy
- 18 - No user responding
- 19 - No answer from user (user alerted)
- 21 - Call Rejected
- 22 - Number changed
- 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.
- 34 - No circuit/channel available
- 38 - Network out of order
- 41 - Temporary failure
- 42 - Switching equipment congestion
- 43 - Access information discarded
- 44 - Requested circuit/channel not available
- 47 - Resources unavailable, unspecified
- 49 - Quality of service unavailable
- 50 - Requested facility not subscribed
- 57 - Bearer capability not authorized
- 58 - Bearer capability not presently available
- 63 - Service or option not available, unspecified
- 65 - Bearer capability not implemented
- 66 - Channel type 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
- 88 - Incompatible destination
- 91 - Invalid transit network selection
- 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
- 111 - Protocol error, unspecified
- 127 - Interworking, unspecified
