show isdn active
Shows ISDN calls in progress
show isdn history
Shows ISDN call history
show isdn status
Shows ISDN line status
show isdn timers
Shows ISDN timer values
debug isdn events
Displays ISDN events in real time
debug isdn q921
Displays ISDN Q.921 packets in real time

debug isdn q931
Displays ISDN Q.931 packets in real time