When the alarm is triggered, how long will it ring for and for how many cycles?

The followings are applicable to model SK618, SK633, SK634, SK642, AND SK662. 

In ARM mode, once triggered, the alarm will ring for 30 seconds, then stop for 30 seconds, then ring again for 30 more seconds, and the dialer will dial out all telephone numbers stored. The dialer remains in ARM mode, ready for next trigger. The dialer will also trigger any linked siren SK626 or AC socket SK635.

You could silence the alarm. Go into programming mode, check OFF the siren. The dialer will not sound when triggered, but it will dial out all pre-programmed telephone numbers.