Migrating to a Different Device Model

If your new device is a different model, but the same type as your old one (for example, you have switched from one BlackBerry model to another), you will need to clear the account data, Mail, and PIM items from the old device before you set up your new device.

More:

BlackBerry to BlackBerry

iPhone to iPhone

Palm OS to Palm OS

Symbian to Symbian

Windows Mobile to Windows Mobile

Windows Mobile ActiveSync to Windows Mobile ActiveSync