Door Access and Intercom systems are part of our everyday life for entry to buildings or areas within a building.  Some of these systems are as simple as a basic voice or voice/video based system with the ability to allow entry.  While others are more complex with the ability for 1,000 names/numbers, scrolling directories instead of paper or touch screens. 

Some systems are stand-alone with direct wiring from a ‘master station’ to remote stations.  The majority are an auto-dialer, using its dedicated phone line to reach the desired party.