Q.931

We have activated pri debugging in asterisk and the Q.931 (isdn signaling protocol) is now exposed. Looking at the sequence

of message types exchanged between the mitel and the Com.X which eventually results in a DISCONNECT from the Com.X to the pri span

with what looks like some sort of coding standard problem.

Please take a look at https://en.wikipedia.org/wiki/Q.931 - there are descriptions of message types and failure codes.

Message type descriptions:

The sequences below are consistent with the summary above. The message exchange sequence:

Looking closer at the disconnect cause:

[Oct 5 10:49:02] VERBOSE[25281] chan_dahdi.c: PRI Span: 2 < Message Type: DISCONNECT (69)

[Oct 5 10:49:02] VERBOSE[25281] chan_dahdi.c: PRI Span: 2 < [08 02 80 90]

[Oct 5 10:49:02] VERBOSE[25281] chan_dahdi.c: PRI Span: 2 < Cause (len= 4) [ Ext: 1 Coding: CCITT (ITU) standard (0) Spare: 0 Location: User (0)

[Oct 5 10:49:02] VERBOSE[25281] chan_dahdi.c: PRI Span: 2 < Ext: 1 Cause: Normal Clearing (16), class = Normal Event (1) ]

[Oct 5 10:49:02] VERBOSE[25281] chan_dahdi.c: PRI Span: 2 -- Got ACK for N(S)=5 to (but not including) N(S)=5

Looking at PRI event processing:

Attached is a pri debug log where I got these sequences from.

You can watch the series of PRI events by executing the following command (provided pri debugging enabled):

> tail -f /var/log/asterisk/full | grep "Processing event"

Or message sequence:

> tail -f /var/log/asterisk/full | grep "Message Type:"