A CDMA iPhone was one of Apple's long term plans when they first launched the first GSM iPhone in 2007. The first iPhone 2G was a GSM phone with a SIM card tray. You simply register with one of the available GSM carriers such as AT&T in the US. You get a SIM card that you plug in the iPhone SIM card tray to get the cell phone and the internet service that this carrier provides.
The iPhone was always a GSM smart phone that came with a regular size SIM card. The third generation iPhone design known as iPhone 4 came with a micro SIM card.
It is easy to modify a full size SIM card to fit in a micro SIM card tray on the iPhone 4 but not the opposite. You can buy some full size SIM card trays that can hold a micro SIM for the new iPhone 4 SIM design. However, for four years, there was no iPhone design that supported the CDMA network.
Apple was loosing lots of customers to Android phones either because they were not able to switch to AT&T or simply because they didn't like At&T. CDMA network in the US is supported by Verizon, and Sprint.
Four years after the original launch of the GSM iPhone design Apple redesigned a new iPhone 4 that is CDMA compatible. It was made to run on Verizon network which is a CDMA network.
Verizon customers are able to enjoy the most popular smart phone and stay with their carrier.
An iPhone was only possible with At&T. I personally switched to AT&T after 15 years with Sprint simply because Sprint didn't offer the
iPhone. There are many customers with Verizon who also switched to AT&T just to get an iPhone. Therefore, having an iPhone 4 under Verizon CDMA network is definitely a great advantage to both Verizon and its customers.
The differences between the two iPhone designs are completely dependent on the the network differences and capability. The table below shows the full list of differences between the two iPhones with their networks.
Advantages of GSM iPhone:
Of course many people were thankful a CDMA iPhone is finally available. But what do you loose when you get a CDMA vs a GSM iPhone.
With a GSM iPhone you can simply switch carriers by removing the iPhone SIM card. Also roaming between different carriers is easier.
One of the most annoying issues I have with CDMA iPhone is that the CDMA network doesn't allow simultaneous data and voice transfer. In other words, you can't talk on the phone and check your email or browse the internet. Some people might argue why you need to access the internet while talking on the phone, I personally use voice and data at the same time in many occasions.
CDMA iPhone also draws more power than the GSM iPhone, therefore lowering the iPhone battery life.
Jailbreak CDMA iPhone:
Probably one of the most important questions you might have if you are planning to buy a CDMA iPhone is the ability to jailbreak it. Yes, you can jailbreak an iPhone with the CDMA design using the same tools used to jailbreak the regular GSM iPhone.
Although unlocking a CDMA might be simple or similar to a GSM iPhone. The problem reside in getting an ESN (Electronic Serial Number) and MEID (Mobile Equipment Identifier). Those numbers are globally unique and usually stamped on the phone itself. They are usually under the smart phone battery in many
This makes it more difficult to run a Verizon iPhone on a Sprint network although they both use the same CDMA network.
With a GSM iPhones you can simply unlock the iPhone by using a software, and then simply replace the the iPhone SIM card with another one from another GSM carrier.
Apple was able to commonise the two iPhones in one single iPhone design called iPhone 4S. The iPhone 4S is a world iPhone design that can work in any network in the world whether it is CDMA or GSM. It intelligently switches between its antennas to roam to whatever network available. So if your home network is CDMA, you can easily roam to a GSM network. Or if your home is GSM, you can easily roam to a CDMA network.