Once Apple unleashed the iPhone 4S on the world Oct. 14, it started selling its older models of iPhone for drastically reduced prices. iPhone 4S famously broke sales records that weekend, but there's no numbers on how many of the iPhone 4 and iPhone 3GS the company sold. iPhone 4 now only costs $99 and the 3GS is now free with a two year contract on AT&T. iPhone 4S and iPhone 4 are both now available on the Verizon and Sprint networks, but why isn't the 3GS included with the deal?

Obviously, Apple still wants to make money, so maybe they don't want to give away all their two year old tech to Sprint and Verizon customers. No, Apple makes money off the free iPhone 3GS because AT&T pays them for it and subsidizes the cost to people who purchase a two year contract. The free iPhone 3GS isn't available on Sprint or Verizon for a completely legitimate reason. AT&T uses a different wireless technology than Sprint or Verizon. The iPhone 3GS only works on what's called the GSM standard. It's the network that sends out signals to your mobile device. Sprint and Verizon use CDMA technology and the signals sent out by those wireless antennas don't match those on the GSM network.

That means iPhone 4 now comes in two flavors, one for AT&T and one for Sprint and Verizon, now that it's been made available for them. iPhone 4S, on the other hand, is what's called a world phone because it has both the CDMA and GSM chip inside, and it works on both networks. As for why Apple went to the trouble to make new iPhone 4's with the CDMA chip and not the 3GS, it may have been too expensive. The 3GS has been around for over two years now, and that is pretty old in the tech world. iPhone 4 was only a year old or so when they decided to add the CDMA, so it may have made sense for them to include it.

Let us know if you were looking forward to getting an iPhone 3GS on Sprint or Verizon only to find out it wouldn't work.