Somebody needs to replace the ubiquitous restaurant buzzer with either an SMS- or smartphone-based tool: when you put your name on the waiting list, you give them your phone number.
When your table is ready, they can buzz your phone.
Fewer moving parts for the restaurant. Fewer chances to lose stuff. Less crap to carry if you’re a customer.
And if you don’t have a phone anywhere in your party? Well, those few folks can get a buzzer.