An intercom (intercommunication device), talkback or doorphone is a stand-alone voice communications system for use within a building.
LEM-1DLS audio door answer and release system by Aiphone
$263.50
Aiphone JOS-1A Access Sentry Kit w/ Intercom & Door Station
$693.60
Doorbird D1101V Video Door Station, Surface-Mount, Stainless, 1080p
$670.77
DoorBird A1101 Indoor IP Video Station, Surface Mounting
$578.34