WEmergency population warning
WCell Broadcast
WCivil defense siren
WCONELRAD
WEastern Ruapehu Lahar Alarm and Warning System
WEmergency Alert System
WEmergency Cell Broadcast System
WEmergency Mobile Alert
WFederal Signal 3T22
WHANDEL
WJ-Alert
WMessageNet systems
WMexican Seismic Alert System
WNational Emergency Alarm Repeater
WNL-Alert
WOpenBroadcaster
WPublic Warning System (Singapore)
WMartje Saljé
WSevernside Sirens
WShakeAlert
WWartime Broadcasting Service