Not helpful if you left it in the car.
Or if the ringers' off, or the battery dead (usually the case by the time I realize I've misplaced it.)
And isn't there usually a landline or friend's cellphone handy to do the dialing anyway?
Ungrateful menschen! Gad zooks. Thanks Gerard.
Well, there's usually a landline around only if you want to pay another $50 a month to have telemarketers call you.
Seriously, I haven't had a landline in years. Can't see the sense of it.
As to ringer off or battery out, well, you can't make the world foolproof.
"We don't keep a record of numbers dialed."
Hmmm... Don't like someone? Want to annoy them, without any way to track that back to you? This seems to me like the ideal harrassment tool.
Sorry if this seems a bit negative, but years of engineering doing worst-case design turns one into a professional pessimist.