I'm a Crackberry newbie, so 'scuse me in advance for what's probably a really dumb question:
On a couple of occasions entering a long phone number (i.e. with area code) that's not stored in my phone book, my VZW 8130 has interpreted my intended "0" as a "+", right in the middle of the number string.
Holding down the zero key is a shortcut way of typing a + when you're putting in a number. If you're getting plusses where you want zeros, you're holding the key too long.