I recently purchased an unlocked Nokia 2730 Classic with the intention of transferring the SIM from my old LG 215 onto my new cell phone. I noticed the SIM from my old phone, a SMART Buddy SIM, was considerably larger than the SIM well or receptacle on the Nokia phone. I wasn't aware until then of the potential physical incompatibility between SIM cards and cell phones with all the talk about how easy it is to transfer SIM cards from one unlocked phone to another. Do SIM card manufacturers produce different size cards for different phones? If so, how do I ensure compatibility when purchasing these cards on the internet when the size of the card is never mentioned?