A national emergency alert system to send concise, text-like messages, which has a unique audible signal and vibration cadence to users' WEA-capable mobile devices. The alert is no more than 90 characters, and includes the following info: who is sending the alert, what is happening, who is affected and what action to take. In response to the WARN Act, passed by Congress in 2006, the messages were intended to complement the existing Emergency Alert System, which broadcasts alerts over radio, television and highway signs. Officially available April 2012, wireless providers representing nearly 97 percent of subscribers are participating in distributing wireless emergency alerts. Also known as Commercial Mobile Alert System (CMAS) or Personal Localized Alerting Network (PLAN).