If you are running R11, and get pkt alarms, you need to check for errs 1 and 257 in the err log, most commonly, with out a patch you will see the mac addess disappear on the "status link XX" page, and it tends to drop all ISDN trunks, a reset 1 will bring all back into service and you could do a disable mo logical 5150 phy 1a to prevent this from happening until a software patch is installed, 5142 or 5333. This was corrected in later loads of R11