The AlertMe app receives alert messages, and notifies the user even when the app is not currently running. If the app is running (visible on the screen), when it receives an SMS, the message will be displayed on the screen. If it's not running, the user will receive a Notification in the status bar, which can be viewed by pulling down the status bar. Tapping on the notification will start the app and display the message. The user can then click the Acknowledge button to send an acknowledgment to the sender that the alert has been received.