ISDN Cause codes meaning

ISDN cause codes are used to describe reasons for hang up. Here is the full list of ISDN codes and their meaning:

• 1. Unallocated (unassigned) number
• 2. No route to specific transit network
• 3. No route to destination
• 4. Send special info tone
• 5. Misdialed trunk prefix
• 6. Channel unacceptable
• 7. Call awarded and being delivered in established channel
• 8. Preemption
• 9. Preemption – circuit reserved for reuse
• 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. Redirect to new destination (unallocated destination number ANSI)
• 24. Unknown business group (ANSI)
• 25. Exchange routing error (ANSI)
• 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
• 39. Permanent frame mode connection out of service
• 40. Permanent frame mode connection operational
• 41. Temporary failure
• 42. Switching equipment congestion
• 43. Access information discarded
• 44. Requested channel/circuit not available
• 45. Preemption (ANSI)
• 46. Precedence call blocked
• 47. Resources unavailable, unspecified
• 49. Quality of service unavailable
• 50. Requested facility not subscribed
• 51. Call type incompatible with service request (ANSI)
• 53. Outgoing calls barred within CUG
• 54. Call blocked due to group restrictions (ANSI)
• 55. Incoming calls barred within CUG
• 57. Bearer capability not authorized
• 58. Bearer capability not presently available
• 62. Inconsistency in designed outg. access inf. and subscr. class
• 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 bearer cap. 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
• 90. Non-existing CUG
• 91. Invalid transit network selection
• 95. Invalid message, unspecified
• 96. Mandatory information element is missing
• 97. Message type non-existing or not implemented
• 98. Message incompatible with call state or mesg type non-existent or not implemented
• 99. Information element non-existent 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

For more info, check this summary.