Technical data

B. Appendixes to optional packages
B.12.2. Error Messages Of The ISDN-Subsystem (i4l-Documentation)
Following is an excerpt from the Isdn4Linux Documentation (man 7 isdn_cause).
Cause messages are 2-byte information elements, describing the state transitions of an ISDN
line. Each cause message describes its origination (location) in one byte, while the cause code
is described in the other byte. Internally, when EDSS1 is used, the first byte contains the
location while the second byte contains the cause code. When using 1TR6, the first byte
contains the cause code while the location is coded in the second byte. In the Linux ISDN
subsystem, the cause messages visible to the user are unified to avoid confusion. All user visible
cause messages are displayed as hexadecimal strings. These strings always have the location
coded in the first byte, regardless if using 1TR6 or EDSS1. When using EDSS1, these strings
are preceeded by the character ’E’.
LOCATION The following location codes are defined when using EDSS1:
00 Message generated by user.
01 Message generated by private network serving the local user.
02 Message generated by public network serving the local user.
03 Message generated by transit network.
04 Message generated by public network serving the remote user.
05 Message generated by private network serving the remote user.
07 Message generated by international network.
0A Message generated by network beyond inter-working point.
CAUSE The following cause codes are defined when using EDSS1:
01 Unallocated (unassigned) number.
02 No route to specified transit network.
03 No route to destination.
06 Channel unacceptable.
07 Call awarded and being delivered in an established channel.
10 Normal call clearing.
11 User busy.
12 No user responding.
13 No answer from user (user alerted).
15 Call rejected.
16 Number changed.
1A Non-selected user clearing.
1B Destination out of order.
1C Invalid number format.
1D Facility rejected.
1E Response to status enquiry.
1F Normal, unspecified.
22 No circuit or channel available.
26 Network out of order.
29 Temporary failure.
2A Switching equipment congestion.
2B Access information discarded.
2C Requested circuit or channel not available.
2F Resources unavailable, unspecified.
31 Quality of service unavailable.
32 Requested facility not subscribed.
368