What happens after a no call no show?
It depends on the employer's policy. Many event agencies stop offering shifts after a single no call no show, because an event can't replace someone at the last minute. Some employers treat several in a row as quitting the job.
Is a no call no show the same as calling out?
No. Calling out means you told someone before the shift that you can't make it. Some agencies still count it against you, but far less than missing a shift without a word.
How to avoid one
Confirm the shift when it's booked, and save the call time and the scheduler's number. If anything changes, message them as soon as you know, even an hour before. A late message is still better than none.