Because the network controls the server, they could have some code in there that says something like:
default id = 12345
if the incoming link does not have a CD id, assign it to the default id
if you wonder why, think about all the people who, for one reason or another, fail to properly include their id in their links. Someone's got to get credit for it.
That will not work - I've had experience with the DirectTrack interface.