[Madmartagen]

GSM phones have SIM cards, CDMA devices do not. If you have a cell phone from ebay, chances are it is not unlocked and thus, you will only be able to use it with the service provider (ex cingular, tmobile) that it was designated for. Verizon is not GSM, so chances are the phone is for ATT, Cingular or TMobile. You can get the phone unlocked from a store or finding out online, but before you buy it on ebay, check around at your local vendors to see if you can get a new model for cheap by signing up.

Also, if it has a SIM card then it is absolutely needs to have one to work. SIM cards are what identify your phone number and the plans that you have on your account. If you have a phone w/o a SIM, you will not be able to place any call over a network and you will not be able to receive any type of signal from any network. They run about $30 from vendors and are included if you buy a contract.