I have a simple, old, cheap cellphone. It has alarms, so I assume that every cellphone does these days. You select the time for an alarm, and then – of course – you select any of your ringtones to announce the alarm.
It took me a while to discover how handy these phone alarms are, but now I use them a lot. I finally realized that they are the answer to an age-old problem: how to get out of a meeting, or some other situation that you wish to escape from. The old-fashioned way was to ask someone to call you at, say, 10:10. Your meeting has barely started when your phone rings. You pretend to talk to your confederate, and then you look up and say to the others, “Sorry, I've got to go.”
Today, you don't even need a confederate. You just talk to one of your phone alarms.