I have a Motorola iDEN i856 phone, from nextel. it has an active SIM card. My mother has a BlackBerry curve. i have swapped SIM's with her phone before , and it worked. i only had them swapped for a small amount of time. A friend of mine wants to sell me a BlackBerry Curve for only $50, and it works, i want to know if i will have any problems if i switched the SIM from my iDEN phone to the blackberry. i regularly Text, Call, and use the internet. i have the Simply Everything plan on sprint / nextel, so i have unlimited data. Does anyone know if i will have any problems?