Strange but it sounds like the cell number was forwarded to somewhere. ATT should be able to fix the problem. On a chance the download caused the issue, have you tried to remove the ring tone? This may be a hard thing to do but do a wipe and start from the beginning and initialize the BB. If your unfimilure with a wipe, all it does is restore to factory the phone and leave nothing on it. You can do a backup for any contacts you have but I would not backup anything else. DM will offer selective data backup and restore. options/security/wipe
If you do not have Desktop Manager go to RIM BlackBerry - Support & Services
then to downloads and get a free copy.