Switching phone numbers between 2 activated phones?

[RIPPIMPC]

Hello! I have two phone lines that are activated, A Palm Pre Plus as my main line and a BlackBerry Cruve as the second line. I want to switch the numbers between the two phones and have the BlackBerry Curve as my main line and put the Palm Pre Plus on the second line. Does anybody know the easiest way in doing so? Also, sometime soon I plan on getting a cheap Verizon pre-paid phone and possibly activating it on the second line, so it replaces the Palm Pre Plus. Is this even possible? I wanna sell my Palm Pre Plus.

[veriztd]

dial *228 to switch devices

[lemew]

You have to have a third phone to start off with.

[XFF]

Also, sometime soon I plan on getting a cheap Verizon pre-paid phone and possibly activating it on the second line, so it replaces the Palm Pre Plus. Is this even possible? I wanna sell my Palm Pre Plus.

A VZW prepaid phone has to be used on prepaid for at least 6 months before it can be activated on a postpaid account.