Enterprise Alert has several ways that you can manually send a notification. The Send Message option is often confused as raising an alert. The Send Message tool is mainly there for testing purposes only. Sending a message is designed to test the connectivity and effectiveness of a notification channel.
The Raise Alert tool can be used for production alerts, however Callouts are better designed for this. The Raise Alert tool is again mainly for testing but gives the user the ability to respond - therefore testing two way communication - such as responding to a SMS to acknowledge an alert.