How do I know I have voice mail?
From PhonePower Knowledge Base
Voicemail alerts come in many forms. You might receive a stutter dial on the handset, a blinking phone light on the phone adapter device or an indication on the phone itself if the phone is capable of displaying a "message waiting" icon.
You can also configure your new Voicemail to be emailed to you either with a .wav attachment or just a notification of that new Voicemail. Please refer to VoiceMail Instructions for more information on setting up the Voicemail to email feature of the Phone Power service.