Guide: How to backup all your contacts / numbers to Google
Other than the normal backup you can perform through the desktop manager, you can backup your contacts to Google incase you ever lose or sell your BlackBerry and still want to view your contacts.
1) You need to have a gmail e-mail account, if you don't then create one, it's free at www.gmail.com
2) On your BB, go to Google, then search for google Sync and install it on your BlackBerry.
3) Sign in Google sync with your gmail account.
4) Hit sync and wait.
All your contacts will be copied to your GMAIL account and you can view the numbers
Easy :D