What are all the differences between the iPhone 4 (AT&T/GSM) and the iPhone 4 (Verizon/Sprint/CDMA)? Which one should I buy?

At first glance, the iPhone 4 models -- the originally released iPhone 4 (GSM), which is available exclusively on AT&T in the US, and the subsequently released iPhone 4 (CDMA), which is available exclusively on Verizon in the US -- look identical.

However, with close inspection, there are a few differences that are readily apparent as well as a few notable differences in functionality and performance that merit attention.

Photo Credit: Apple, Inc. (GSM Model - Left, CDMA Model - Right)

External Differences

Both models use the same general all stainless steel body design and a thin "metal band" that wraps around the sides of each phone. However, the GSM model has an access panel on the right side (and an enclosed Micro SIM card) and the CDMA model does not have an access panel or a SIM card.

Although it can be a bit of a challenge to see in the promotional photos above, the GSM model -- on the left -- also has three antenna "breaks" in the metal band (one on the top and one on each side toward the bottom) and the CDMA model -- on the right -- has four (two on both sides toward the top and bottom).

In the introductory press conference, Apple's Tim Cook stated that this change is merely related to the CDMA antenna, rather than any effort to improve the GSM model's much ballyhooed "death grip" reception issues. In preliminary testing, MacWorld reported that the reception no longer was an issue whereas AnandTech found that it still was possible to degrade the signal when the CDMA model was held "improperly." AnandTech also noted that the "dual-receive antenna architecture is something that Verizon refers to as 'antenna diversity' and it's a part of Verizon's spec for devices on its network."

In an in-depth review after the device shipped, the always excellent iLounge found that "signal attenuation" still could be an issue for the CDMA iPhone 4 as demonstrated in this video:

For most users, antenna issues have not been enough of a problem to discontinue using an iPhone 4 (and wrapping either the GSM or CDMA model with a case will resolve the issue), but it is worth noting that if one finds the antenna to be a problem on a GSM iPhone 4, it is likely that it still would be a problem with a CDMA version as well.

One would have to be awfully precise to be able to tell the difference without the devices side-by-side, but the CDMA version also has the left-hand buttons slightly lower to accommodate the different antenna placement, and this means that some cases that fit the GSM version will not fit properly on the CDMA version without modification if at all.

Identification Differences

One simple way to identify the iPhone 4 models, as well as all other iPhone models, is by the model number printed in small type on the back of the phone.

The model number printed on the back of the GSM-equipped iPhone 4 is A1332 and the model number on the back of the CDMA-equipped iPhone 4 is A1349. The subsequently introduced model iPhone 4S -- which looks effectively identical to the iPhone 4 models -- has model number A1387 on the back.

Everyi.com's Ultimate iLookup feature also can identify these iPhone models by EMC number, order number (referred to as "model" in software), and the last three or four characters of their serial numbers as well (the last three characters for devices with an eleven character serial number and the last four characters for devices with a twelve character serial number).

Functional Differences

From a functional standpoint, the major change is that the GSM-equipped iPhone 4 supports the EDGE "2G" mobile wireless standard as well as 3G networking (7.2 Mbps HSDPA support and HSUPA networks for compatibility with more cellular carriers worldwide). The iPhone 4 (CDMA) model, on the other hand, instead supports CDMA (EV-DO, Rev. A, 800 MHz, 1900 MHz), which means that global coverage is considerably more limited.

Other limitations of the CDMA model include the inability to receive voice and data simultaneously and slower data altogether, the inability to place a call on hold and conference calls are limited to two calls rather than five. These limitations are due to the older CDMA standard rather than the phone itself. Verizon was the first to announce support for a then new "Personal Hotspot" capability that makes it possible to use the iPhone to connect up to five Wi-Fi enabled devices (AT&T offers similar "tethering" capability although it is possible to make and receive calls as well as use the Internet simultaneously).

Battery Life Differences

Battery life also is a bit different due to support of GSM and CDMA networks, respectively. Audio playback, video playback, talk time on 3G, Internet use on Wi-Fi, Internet use on 3G, and standby time all are reported to be the same. However, the GSM-equipped model can provide an estimated fourteen hours of talk time over a 2G network, whereas the CDMA-equipped model does not support a 2G/EDGE network, and consequently is limited to talk time of 7 hours over a 3G network (which is the same talk time for the GSM model over a 3G network, too).

Device Similarities

Other than the differences enumerated above, the GSM-equipped and CDMA-equipped iPhone 4 models are identical. Experts may choose to stop reading now, although others may find the below -- which explains the capabilities that both devices share -- helpful as well.

The iPhone 4 models both have the same high-resolution 960x640 at 326 ppi 3.5", IPS, LED-backlit display with an 800:1 contrast ratio that Apple refers to as a "retina display." The iPhone 4 also has a chemically hardened "aluminosilcate" glass front over both the display and although it was originally announced on June 7, 2010 with a white or black frame and a chemically hardened white or black glass back as well, only black was available for either the GSM-equipped or CDMA-equipped model until April 28, 2011, when both models finally were available in white as well.

The iPhone 4 models have dual cameras -- a 5 megapixel HD video/still camera (720p at 30 FPS) with a "backside illuminated sensor," a 5X digital zoom, and an LED flash on the rear and a VGA quality video/still camera on the front designed for video conferencing over a Wi-Fi network with Apple's included "FaceTime" application. The iPhone 4 has dual noise-canceling microphones as well.

The iPhone 4 models have a variable speed 1GHz "Apple A4" processor that commonly runs around 750-800 MHz and 512 MB of RAM, support Bluetooth 2.1+EDR as well as Wi-Fi (802.11b/g in addition to the 2.4 GHz frequency of 802.11n). Both models include an accelerometer, proximity sensors, an ambient light sensor, A-GPS, a digital compass, and a three-axis gyroscope. Both are offered with either 16 GB or 32 GB of storage, too.

Pricing Similarities

Pricing in the United States for the GSM-equipped iPhone 4 and CDMA-equipped iPhone 4 essentially are the same. As introduced, AT&T offered the GSM version with 16 GB or 32 GB of storage for US$199 and US$299, respectively. Verizon offered the CDMA version with 16 GB or 32 GB of storage for US$199.99 and US$299.99 (Apple sold the Verizon phone for 99 cents less).

On October 4, 2011, upon introducing the iPhone 4S, Apple also introduced an 8 GB configuration of both the GSM and CDMA-equipped iPhone 4 models for US$99. The GSM version is available locked to AT&T and the CDMA version is available locked to either Verizon or Sprint.

AT&T, Verizon and Sprint require, or required, a two-year contract for these prices. These models also are available unlocked at a higher price.

Comparison Chart

For your convenience, the main differences between the iPhone 4 (GSM) and iPhone 4 (CDMA) models also have been summarized below:

	iPhone 4 (GSM)	iPhone 4 (CDMA)
Standard Storage:	8, 16, 32 GB*	8, 16, 32 GB*
GSM/EDGE:	Yes	No
UMTS:	Yes	No
HSDPA:	Yes	No
HSUPA:	Yes	No
EV-DO:	No	Yes
Personal Hotspot:	No	Yes
Talk Time (3G):	7 Hours	7 Hours
Talk Time (2G):	14 Hours	None
Battery Life (Web - 3G):	6 Hours	6 Hours
Battery Life (Web - Wi-Fi):	10 Hours	10 Hours
Battery Life (Music):	40 Hours	40 Hours
Battery Life (Video):	10 Hours	10 Hours
Standby Time:	300 Hours	300 Hours
SIM Card:	Micro	None
OS Support:	iOS 4.0+	iOS 4.3+
Order No (As Introduced):	MC318LL/A, MC319LL/A	MC676LL/A, MC678LL/A
Model No:	A1332	A1349
Price (As Introduced):	US$199, US$299*	US$199.99, US$299.99*
Price (Current):	US$99*	US$99*

*On October 4, 2011, Apple introduced a low-end 8 GB configuration and discontinued the 16 GB and 32 GB configurations. The 16 GB and 32 GB configurations cost US$199 and US$299, respectively, and the 8 GB model is US$99. These prices all require a two-year contract in the US.

So, which one should I buy?

Ultimately, which iPhone 4 to buy is your decision, if either, but the devices essentially are the same price and AT&T, Verizon and Sprint plan pricing is quite similar as well.

Those who travel globally on a regular basis are more likely to find the GSM model worthwhile as the CDMA standard is considered obsolete in many places. On the other hand, Verizon and Sprint both have the reputation for greater reliability in the US, whether or not it is justified, and many may find reliability to be more important than simultaneous voice and data use, data network speed, or global compatibility. The choice may very well come down to which network is most reliable in your area.

Also see:

• What are all the differences between the iPhone 4S and the iPhone 4? Which one is best for my needs?
• What are all the differences between the iPhone 4 and the iPhone 3GS?
• What are the main differences between each iPhone -- the iPhone 4S, the iPhone 4, iPhone 3GS, iPhone 3G and the original iPhone? How can each be identified quickly?