Emergency Warning Intercom System or EWIS as they are more commonly known are generally installed in conjunction with a fire alarm system when required. They can also be installed as a standalone emergency and evacuation system. They are an audible alarm and intercom system designed to alert the occupants of a building that there is pending danger. They can be manually triggered or activated by a fire alarm system.
An EWIS can also be used for paging and background music throughout a building and will sound a warning and evacuation tone when triggered for an emergency.