two keys paging press button used for restaurant, hotel, hospital, etc. 

call bill cancel waterproof press button used in restaurant, hotel, etc.

three keys call cancel bill press button used in restaurant, hotel, etc.

call bill cancel three keys press button used in restaurant, hotel, etc.

set on table press button used in restaurant, hotel, etc.

guest press button used in restaurant, hotel, etc.

guest press calling button used in restaurant, hotel, etc.

press call button used in restaurant, hotel, etc.

one key call button used in restaurant, hotel, etc.