Information Technology Reference
In-Depth Information
Table17-9
ISDN Cause Code Fields
y2
0-User
1-Private network serving local user
2-Public network serving local user
3-Transit network
4-Public network serving remote user
5-Private network serving remote user
7-International network
A-Network beyond internetworking point
Class (the more significant hexadecimal number) of cause value. Refer to
Table 17-10 for detailed information about possible values.
z1
z2
Value (the less significant hexadecimal number) of cause value. Refer to Table
17-10 for detailed information about possible values.
(Optional) Diagnostic field that is always 8.
a1
a2
(Optional) Diagnostic field that is one of the following values:
0-Unknown
1-Permanent
2-Transient
Cause Values
Table 17-10 lists descriptions of some of the most commonly seen cause values of the cause information
element—the third and fourth bytes of the cause code.
Table17-10 ISDN Cause Values
Hex Value
Cause
Explanation
81
Unallocated
(unassigned) number
The ISDN number was sent to the switch in
the correct format; however, the number is
not assigned to any destination equipment.
90
Normal call clearing
Normal call clearing has occurred.
91
User busy
The called system acknowledges the
connection request but is incapable of
accepting the call because all B channels are
in use.
92
No user responding
The connection cannot be completed
because the destination does not respond to
the call.
93
No answer from user
(user alerted)
The destination responds to the connection
request but fails to complete the connection
within the prescribed time. The problem is at
the remote end of the connection.
