Security keyboards
— keyboards for ACS can have a different design and purpose. All of them have a standard set of 12 buttons (10 digital buttons from 0 to 9 plus "*" and "#"), but additional equipment and functionality (both general and special) can differ markedly from model to model. So, some devices of this type are intended for entering access codes; others also allow you to communicate with a particular room (on the principle of an intercom); still others are full-fledged panels for controlling the alarm system, etc. The keys can be either mechanical or touch-sensitive; and additional equipment may include a built-in reader for cards, key fobs, etc. (see "readers"), its own display, backlight system, speaker with microphone, and more.
Note that if the keyboard is equipped with a fingerprint sensor, it does not belong to this category, but to fingerprint readers (see the relevant paragraph).