phone_intercomGSI services and installs several types of phone and intercom systems. Small office or residential phone systems are not only used to make outside calls. Phone systems are also used to communicate from room to room or with someone who may be at an entrance. For large multiple tenant buildings an intercom system could notify tenants of guests in the lobby or at the main entrance. Intercom systems can also display live video of who is calling. For more information visit the sections listed above.