During my periodic oncall weeks I carry a pager pretty much 24x7 (except in the shower and at night, when I put it under my pillow). It's always set to vibrate only, so it doesn't disturb anyone else. One night I woke up several times hearing a vibration only to discover there was no message on it. After about the third time, I realized my wife was snoring.
I've also been "paged" out of a dead sleep by semi truck's Jake Brakes out on the highway, even when not oncall.
I'll be SO glad when I no longer have to ever be oncall again.
Someday.
Maybe.