ESN question

[jbearamus]

actually gsm and cdma do matter. sprint can only activate a cdma device, assuming you can actually get them to do it. its all in the technology running the phone, sprint's network is cdma so you have to get the corresponding phone which basically means sprint or verizon, and cricket or a few other less notable regional carriers.
something to consider though, since its a new line of service sprint is going to require a 2 year agreement whether you provide your own hardware or not so you will probably want to look at getting a new phone from sprint