The Alpha Communications IA543 Power Pack Amplifier is a self-contained unit not requiring an external amplifier. The IA543 is designed for use with 5, 4 or 3 wire apartment speaker type stations and provides amplification, control and power circuits needed to operate a complete apartment intercom system. Voice volume control and tone volume control are easily adjustable through the screwdriver slot on the front panel. It is also a direct replacement for the previous model(s) PK543 and PK543A.

Additional functions include multiple entrance operation with the IA502; AC, DC or Maglock configurations with three (3) selectable door timing modes; post office door lock release; steady or warble call tones; power LED; selectable door button hold timeout; and selectable Talk before door interlock.