CDMA phones had no SIM cards and needed to be authenticated by the service provider, which made unlocking a phone impossible. You could also put a different SIM card in your unlocked phone, and your phone would then work with whatever phone number and account was linked to that card. You could take the SIM card out, put it into another phone, and if someone called your number, the new phone would ring. Part 1: How to transfer SIM card to new phone Part 2: How to copy data out of SIM card to new. It contains all your contacts and settings, and it's linked to your account. Fortunately, this tutorial is going to tell you the best method to transfer SIM card to your new cell phone, and you can also learn how to transfer other files out of SIM card from the old device to the new one. A SIM card is a small card that's inserted into the phone. What's the difference? GSM phones used subscriber identity module (SIM) cards. However, if your phone operated on a GSM network, then it might be unlockable. If you had a CDMA phone, then your phone was unlockable. There used to be two cellphone technologies that were used by the majority of the world's mobile phone service providers: Global System for Mobile communication ( GSM) and Code Division Multiple Access (CDMA). Some phones even have space for two SIM cards, useful if you do a lot of international travel. You can switch out the card to use another cellphone company.
