Yes, I have used it, and the one on the Xstream as well.
It is a useful function, but it can only monitor the D channel messages between itself and the CO switch. In other words you cannot use it as a protocol analyzer between any terminal and any switch.
It does come in handy now and then when trying to make a PBX emulate a network switch to the Zephyr.
Since you know the com port command line you just need to do a "log ?" and you will find the commands to turn it on (I am rusty - On the pre 2.5x software it was "Log 7", then it changed to "log isdm imon" I think, but I know my brain is confused between the to Zephyr and the Xstream.
If you turn on layer 2 (link layer) as well as Layer 3 (dialing layer) it is quite verbose. Generally the Layer 3 is most useful.
Here is the stickler, unless you invest in the various bellcor specs it is very hard to prove which end is not complaint.
Here are a couple of cool tricks though;
1) When a call disconnects there is a "cause value" generated and sent to both ends. The Zephyr gives thee as decimal values but the Xstream does not. The decimal value will give you a good idea with messages like "normal disconnect", "no user responding" etc. My favorite is 111 "protocol error unspecified".
However, in addition to the value there is a "location" associated with the cause value. This information can be very useful.
If you ask David Jablonski to dig in his old emails he should have one that describes how to decode the Xstream's analyzer's cause values and also location bits.
I compiled the most complete chart of cause values that exist and it is on their site.
2) If you have an ISDN line that is actually National ISDN 2, rather than National ISDN 1, you may be able to determine your spids.
First disconnect the ISDN from the unit. Next enter the following as your spid (spid 1 only) 01010101010101. Enable the protocol analyzer, then plug in the ISDN.
You will see the Spid sent in the Zephyr>CO direction. You should then see two spids in the reverse direction, coming FROM the switch.
Sadly, this only works on a small percentage of lines, so it did not make sense to bring this out to the user level which would have been a lot of work for only a few customers.
SO there you have it.
