Icons on default theme

Hi

I use the AT & T default theme. There are three different notifications on thee screen. One of them is new mail message and the other is blackberry messenger. The third one looks like a old cassette with 1 written next to it. I am not able to set it or understand how to set-up the notifications (new messages, messenger) on the top of the screen.

Need help !

Tools

The "old cassette" signals you have a voicemail.

Thanks a lot...I have been trying to crack my head around that for sometime now:)