Ya sure your Nokia 2600 mobile will work in USA with their local GSM sim only if it is unlocked one .Else if the phone is locked to some other network provider in other country then you can't use it with any other GSM sim until you unlock .You can easily unlock your Nokia 2600 mobile using sites like ClassicUnlocking.com they are rendering network unlock code for all mobile models at reliable cost ...After unlocking it you can freely use it with any GSM sim ...