How to make the waiter notice you and not become his enemy at the same time

I do not know about you, but I always lacked a bell button in all catering establishments, where some customer service is expected in the hall, the waiter’s call on the table.

I always wondered why they were never anywhere - but one friend who had recently served as waiters explained that in this case the staff, which is usually not enough, would be completely off the table, rushing from table to table on demand impatiently calling visitors.
')
The “design” solution came instantly: even now, in most establishments, the waiters have something like a PDA, where they enter order data - and so, it’s enough just to give one sound or vibrating signal after a call to the device, and when you press the button again A table is enough to blink an icon with its number, for example. I give the idea to all sufficiently progressive owners of cafes and restaurants - just do not forget to indicate copyright =)

And what ideas or intellectual and technical ways to improve the service sector do you have? Who can not sleep - let's think about it together.