If your phone gets confused and thinks you have voicemail when you don’t:
- Call yourself from another phone
- Leave a voicemail
- Retrieve the voicemail from your cellphone
- Delete the voicemail with “7”
- Exit the system with “*”
Worked for me! Thanks to the Cingular forums for the tip. BTW, the only way I know to unlock the phone is to call Cingular and ask them to do it.