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You have to check with your provider to see if the new phone is compatible with their network. If it is, then you can buy it anywhere. But you'll pay through the nose if you buy a phone without buying the service.

It really depends on your provider - If you have a GSM phone with a SIM card, then yes it is possible and all you need to do is buy a phone that your provider supports and is GSM and has a SIM card (I did exactly what you are asking about - Changed out my old Motorola v60i for a Razr3). eBay has a good variety of phones that are unlocked (usable with most any service) for decent (not great) prices. But, the most important thing is to check with your provider first - would hate to buy a $300 phone only to find out that it does not work with a given provider. Hope that helps.

Your new phone will either have to be unlocked.

Or you will have to buy one that is compatable with your vendor.

Verizon, Sprint, and most other cell providers will lock the phone so it cannot be used on an different carriers system.

Lee

If you buy it anywhere, be prepared to reprogram it everytime the other provider updates their system. Some are daily ! Downloads their local system settings to the phone ! My other provider cell only worked 1 day at a time, without reprogramming !

FYI - only used it 3 days and reprogrammed it 4 times !