Always call them, everybody has a cell phone. Tell them if no contact, then no service. Every time I've heard the majic words "Oh, I'll be there, just come" there would not be anybody home. If they insist, I tell them to call me when they get home and THEN I'll put them into the queue, maybe they can have immediate service, maybe somebody else will be in that appointment time.
Some people think that an 11-12 appointment window is a suggestion for when THEY should show up.
This time of the year is the worst because people are out Christmas shopping and they think that they can just blame traffic on their tardiness and we are supposed to understand.
I've had a few liars who have said they were home, but weren't.
On the southside of town, there are some people who will call, make an appointment, then when you call to tell them you're on the way, they'll answer the phone and just hang up on you.