When you disarm the system after an alarm it will send an abort signal to the monitoring center. If they received the abort signal before they call, then the operator will disregard as long as it is a burglary alarm. It usually takes them 15-20 seconds to call in my experience, so there is a pretty decent window to cancel it. I believe they will still call for all other alarm types.
If you have a dialer delay enabled, then the alarm signal won’t be sent to the monitoring center until the timer runs out. If you disarm before the timer runs out, then the signal won’t be sent.
Default procedures can be found here if you need them.