it means the caller can wait 15 seconds in the queue. That seems humanly too long to wait, so caller might hang up by itself before the end of the queue. therefore your congestion will decrease… but it’s fake 🙂
(note: don’t put 15s on all your cells, because there is a limit on the total number of calls in queue at BSC level)
altogether, i think you can play around with GPRS parameters (max pdch and the high load gprs), and then reduce the T11 down to a more normal value (6 to 10 s)
Well, try and see…
keep me posted,
pix