A number isn't GSM or CDMA, a phone, however, is. And they can't be swapped. GSMs will only work on GSM networks, and CDMAs will only work on CDMA networks. You can, however, probably find a GSM carrier similar to the CDMA one you are considering. Or you will have to get a new phone that is CDMA.
These should help you figure it out. If you are in the US that is.
A number isn't GSM or CDMA, a phone, however, is. And they can't be swapped. GSMs will only work on GSM networks, and CDMAs will only work on CDMA networks. You can, however, probably find a GSM carrier similar to the CDMA one you are considering. Or you will have to get a new phone that is CDMA.
These should help you figure it out. If you are in the US that is.