My sister has a resourceful and cunning beagle that has the uncanny ability to escape from any backyard. Is there some kind of device that can warn the owner/babysitter when the dog has wandered out of bounds? Something that can be worn on the collar, and another sensor that sends an alarm or dials a pager? Like that device in that sci-fi movie where prisoners get their heads blown off if their collar goes out of bounds, for example...what was the movie called? Hmm. Except I don't want the exploding part.