From 2007 through 2013, Apple released eight versions of its popular iPhone. Telling one model from another can be difficult, especially if you are buying one used. While the iPhone's Settings can tell you a lot about an iPhone, it won't tell you much about the hardware. Looking at your iPhone's model number on the back -- not the one in Settings -- will tell you which model you have. If the model number is illegible -- or if you're over 40 without a magnifying glass -- compare its physical characteristics with other iPhones to figure out what you have.
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The Original iPhone
If you bought your iPhone in 2007, it's guaranteed to be an original. This is the year the iPhone was released. Look for the model number "A1203" on the back of its anodized aluminum case. The serial number is also on the back, etched directly into the metal. The front of the iPhone is black and the edges of the case are beveled. On the side is a mini-SIM tray. The phone has a maximum storage of 4GB, 8GB or 16GB. No other iPhone came in a 4GB version.
The iPhone 3G and 3GS
Released in 2008, the iPhone 3G has the model number "A1241" printed on the back. The iPhone 3GS was released in 2009 with the model number "A1303" on the back. The iPhone 3GS was the first iPhone available in black or white; the 3G was only available in black. Both have beveled edges and a plastic back case. The serial numbers are printed on the mini-SIM tray located on the side of the phone.
The iPhone 4 and 4S
The iPhone 4 and 4S have different model numbers on the back that differ for CDMA and GSM technology. US Cellular, Sprint and Verizon use CDMA phones, while AT&T and T-Mobile use GSM phones. The iPhone 4 CDMA model has the "A1349" model number. The iPhone 4 GSM model number is "A1332." The iPhone 4S CDMA model uses "A1387" and the GSM model uses "A1387." The front and back of these phones are made of glass with a stainless steel edge. Volume buttons are engraved with a "+" and "-" sign. SIM trays are on the right edge, except the CDMA iPhone 4, which has no SIM tray.
The iPhone 5, 5c and 5s
Apple made the screen bigger on its iPhone 5 models and introduced a fingerprint scanner on the iPhone 5s. As with all other models, Apple's iPhone 5 models have model numbers on the back. The model number "A1429" indicates it's either a GSM or CDMA iPhone 5. If your model number is "A1428," it's a GSM iPhone 5. A GSM iPhone 5C has the model number "A1532," "A1507" or "A1529." A CDMA iPhone 5C uses "A1532" or "A1456." The model number for a GSM iPhone 5s is "A1533," "A1457" or "A1530." A CDMA iPhone 5s has either "A1533" or "A1453" as a model number. All these models have a SIM tray on the right side, and the front is made of glass. The back of the iPhone 5C is made of plastic, while the 5 and 5s have aluminum backs. An iPhone 5 is either black or white. The back of an iPhone 5c is white, blue, pink, green or yellow. The back of an iPhone 5s is gray, silver or gold.
Spotting a Fake iPhone
As with other popular products, a lot of counterfeit iPhones are on the market. These can be hard to spot until you look at the phone's engineering. The case may be plastic, when the original version should be glass or aluminum. The SIM trays may be on the back of the phone, which is never the case on an authentic model. Volume buttons may wiggle or feel loose, and the Home button may make a plastic-sounding click. Screen resolution is usually poor on counterfeits. All in all, a cheap counterfeit looks and feels cheap when it's in your hands.