An unlocked cell phone is one that is not tied into a certain carrier’s network: It will work with more than one service provider. Most phones are tied—or locked—to a certain.
• Uses encryption to make phone calls more secure • Data networking • Group III facsimile services • Short Message Service (SMS) for text messages and paging • Call forwarding • • Call waiting • Multi-party conferencing GSM operates in the 900 MHz band (890 MHz - 960 MHz) in Europe and Asia and in the 1900 MHz (sometimes referred to as 1.9 GHz) band in the United States. It is used in digital cellular and PCS-based systems. GSM is also the basis for Integrated Digital Enhanced Network (iDEN), a popular system introduced by and used. The incredible growth of GSM is a big part of why the acronym is now commonly thought of as standing for the Global System for Mobile communications! How To Unlock Iphone 5 Without Erasing Everything. If you were on a cell phone in Europe, you'd be using the GSM service.
This topic is important when it comes to unlocking a GSM or CDMA phone because they don’t both work in the same way. It is because of the differences between them in regards to the hardware they use to connect to a network (SIM card versus no SIM card). In simple terms, GSM handsets use what is known as a Subscriber Identity Module (SIM) card. The more popular of the two technologies, GSM phones are found in most markets worldwide. This is largely because of the fact that GSM technology was the first of the two and when mobile phones started becoming popular in the late 1990’s, they offered better signal coverage. GSM networks are currently the only type of network used in the UK and many other countries.
The SIM card itself is usually extremely accessible for the phone's owner as well, usually placed under the phones battery. It can be removed and replaced easily, allowing owners to switch between networks without a problem (if the phone is unlock - which if your GSM handset still needs unlocking). CDMA handsets don’t use a SIM card. Instead they connect to a network because that networks details are programmed into the handset itself. Therefore, when the phone is switched on, it automatically connects to the network whose details are embedded inside.