ISDN Cause Values These cause codes indicate the reason for ISDN call failure or call completion:  Cause  Code Description 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 inquiry 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 The Cause is divided into three fields. The most significant bit (bit 8) is always coded as 1. The Class (bits 5 through 7) indicates the general nature of the event. The Value within the Class (bits 1 through 4) indicates the event. Classes and Values should be coded as shown below. Some cause elements may also include an optional Diagnostic octet.  Class 000, Normal Events: Bits 7 6 5  4 3 2 1  Hex  Value Description ----------------------------------------------------- 0 0 0  0 0 0 1  81   1     Unallocated number 0 0 0  0 0 1 0  82   2     No route to specified                             transit network 0 0 0  0 0 1 1  83   3     No route to destination 0 0 0  0 1 1 0  86   6     Channel unacceptable 0 0 0  0 1 1 1  87   7     Call awarded 0 0 1  0 0 0 0  90   16    Normal clearing 0 0 1  0 0 0 1  91   17    User busy 0 0 1  0 0 1 0  92   18    No user responding 0 0 1  0 0 1 1  93   19    User alerting, no answer 0 0 1  0 1 0 1  95   21    Call rejected 0 0 1  0 1 1 0  96   22    Number changed 0 0 1  1 0 1 0  9A   26    Non selected user clearing 0 0 1  1 0 1 1  9B   27    Destination out of order 0 0 1  1 1 0 0  9C   28    Invalid number format 0 0 1  1 1 0 1  9D   29    Facility rejected 0 0 1  1 1 1 0  9E   30    Response to STATus ENQuiry 0 0 1  1 1 1 1  9F   31    Normal unspecified Class 010, Network Congestion: Bits 7 6 5  4 3 2 1  Hex  Value Description ------------------------------------------------------ 0 1 0  0 0 1 0  A2   34    No channel available 0 1 0  0 0 1 1  A3   35    Call queued (AT&T) 0 1 0  0 1 1 0  A6   38    Network out of order 0 1 0  1 0 0 1  A9   41    Temporary failure 0 1 0  1 0 1 0  AA   42    Switching equipment                            congestion 0 1 0  1 0 1 1  AB   43    User info discarded 0 1 0  1 1 0 0  AC   44    Requested channel not                            available 0 1 0  1 1 1 1  AF   47    Resources unavailable                            -unspecified Class 011, Service or Option Not Available: Bits 7 6 5  4 3 2 1  Hex  Value Description ------------------------------------------------------ 0 1 1  0 0 1 0  B2   50    Requested facility not                            subscribed 0 1 1  0 1 0 0  B4   52    Outgoing calls barred                            (AT&T) 0 1 1  0 1 1 0  B6   54    Incoming calls barred 0 1 1  1 0 0 1  B9   57    Bearer capability not                            authorized 0 1 1  1 0 1 0  BA   58    Bearer capability not                            presently                            available 0 1 1  1 1 1 1  BF   63    Service or option not                            available Class 100, Service or Option Not Implemented: Bits 7 6 5  4 3 2 1  Hex  Value Description -------------------------------------------------------- 1 0 0  0 0 0 1  C1   65    Bearer capability not                            implemented 1 0 0  0 0 1 0  C2   66    Channel type not implemented 1 0 0  0 1 0 1  C5   69    Requested facility not                            implemented 1 0 0  0 1 1 0  C6   70    Only restricted digital                            available 1 0 0  1 1 1 1  CF   79    Service not implemented,                            unspecified Class 101, Invalid Message: Bits 7 6 5  4 3 2 1  Hex  Value Description ---------------------------------------------------------- 1 0 1  0 0 0 1  D1   81    Invalid call reference value 1 0 1  0 0 1 0  D2   82    Channel does not exist 1 0 1  0 0 1 1  D3   83    Suspended call exits, call                             identity does not 1 0 1  0 1 0 0  D4   84    Call identity in use 1 0 1  0 1 0 1  D5   85    Invalid digit value for number 1 0 1  0 1 1 0  D6   86    Call identity cleared 1 0 1  1 0 0 0  D8   88    Incompatible destination 1 0 1  1 0 1 1  DB   91    Transit network does                            not exist 1 0 1  1 1 1 1  DF   95    Invalid message, unspecified Class 110, Protocol Error: Bits 7 6 5  4 3 2 1  Hex  Value Description ----------------------------------------------------------- 1 1 0  0 0 0 0  E0   96    Mandatory information element                            missing 1 1 0  0 0 0 1  E1   97    Message type non-existent                             or not implemented 1 1 0  0 0 1 0  E2   98    Message not compatible with                            call state 1 1 0  0 0 1 1  E3   99    Information element not                            implemented 1 1 0  0 1 0 0  E4   100   Invalid information element                            contents 1 1 0  0 1 0 1  E5   101   Message not compatible with                             call state 1 1 0  0 1 1 0  E6   102   Recovery on timer 0 1 1 0  1 1 1 1  EF   111   Protocol error, unspecified Class 111, Interworking: Bits 7 6 5  4 3 2 1  Hex  Value Description ------------------------------------------------------- 1 1 1  1 1 1 1  FF   127   Interworking, unspecified