Locked my keys in the car this morning, pumping gas en route to yoga. I opened the passenger side door to clear out some trash, left the keys on the passenger seat. A few seconds after I closed the door, I heard the ominous click of the car doors locking. No idea how that happened; the automatic door locks are pretty smart - I've tried to to this in the past without success. Best I can guess, the door lock button was inadvertantly pressed as the keys were sitting.
Anyway, I have OnStar - came with the car with a free year subscription and I've procrastinated killing off the subscription. Found the toll free number on the little window sticker, and borrowed the gas station phone to call. Took about 3 minutes (an extra minute because I never updated the subscription with my new address / phone number) but the satellite unlocked my car. Was not even late for yoga.
Once upon a time, pay phones would have been ubiquitous. And remarkably, there was a working pay phone in the lot, but for some reason, it did not seem to want to dial OnStar's toll free number, and I had no quarters to mess around with it.
I understand OnStar has smartphone apps that are cool and powerful; though they do not work for my vintage device (it's a 2007 car). Next vehicle, perhaps.
Had OnStar not been active, would have been a minor annoyance - I was about a mile from home, and could have walked home, gotten my hide-a-key to get into the house, and gotten my spare car key. But this worked faster!