Cool as she is, the iPhone 4S' new personal assistant Siri hasn't been able to tell me in a meaningful way which iPhone 4S offers the fastest data speeds. In the end, I resorted to the usual do-it-yourself approach: a real-world test. And the results were interesting.
Prior to the testing, I expected some big differences between the iPhone 4 and the iPhone 4S (both GSM versions), since the iPhone 4S supports AT&T's faster HSDPA 14.4 network, which is capable of reaching an upload speed of 14.4Mbps and download speed of 5.8Mbps, theoretically twice the speeds of the iPhone 4.
This wasn't always the case, however, and sometimes it was quite the opposite. But first let's talk about how the testing was done.
How we test
It's generally hard to figure out the way to get the best picture of how fast a mobile cellular Internet device's data rate is. The truth is that the speed of a cellular Internet connection varies a great deal from one location to another. It also depends on the server on which the app's data resides and sometimes even on the time of day.
For the testing, I used the Speedtest.net mobile app, which is the most popular app for the purpose. The app automatically connects to a nearby server to download and upload data. How busy the server is during the test affects the scores, but the app still offers a good representation of data speeds in a local area.
I gathered iPhone 4Ses from AT&T, Verizon, and Sprint, and tested the three smartphones against an iPhone 4 at a few well-known places in San Francisco: CNET's lobby, Union Square, and the Fisherman's Wharf area of Pier 39. I picked the first location for an obvious reason: it's the lobby of the building where I work, which is near the Financial District. The others are two of the most popular spots in the city, with lots of people using their phones. Also, I tested three 4G hot spots from various carriers for a comparison.
Keep in mind that these tests only evaluate data speeds for these phones in San Francisco and are not designed to be representative of data speeds you'll find in your area. However, they at least should show how the data speeds compare between each carrier version of the iPhone 4S, as well as the difference between AT&T's iPhone 4S and the iPhone 4.
I started out at CNET's offices, where variable AT&T iPhone reception has plagued me and my co-workers for years. Unfortunately, it was the same experience with the iPhone 4S, maybe even worse. Indeed, not only was the iPhone 4S' 3G cellular data connection actually slower than the iPhone 4's, but also the new phone constantly switched to EDGE instead of 3G. After many trials, I was able to do three tests on a 3G connection that averaged a dismal 170Kbps for download and an even worse 40Kbps for upload. The iPhone 4, on the other hand, was able to offer about 668kbps and 254kbps for download and upload, respectively.
The only explanation I have is that AT&T's iPhones continue to have trouble with the hand-off between the EDGE and 3G networks (something we've seen with all previous versions of the device). Unlike the iPhone 4, the iPhone 4S doesn't include the option to put the phone in either 3G or EDGE mode manually, and maybe it was operating in EDGE mode without indicating that on the screen. Yet, this didn't explain why the iPhone 4 did much better.
When I moved to different locations in town, the AT&T iPhone 4S showed much better performance, though not always outdoing the iPhone 4. At Union Square, for example, the iPhone 4S averaged about 3,004Kbps for download, slower than the iPhone 4's 3,454Kbps. It's faster at uploading, however, at 837Kbps compared with 693Kbps of the iPhone 4.
Finally, at Pier 39, the iPhone 4S showed that it could really beat the iPhone 4 with 4,290Kbps download speed and 1,173Kbps upload speed, compared with 2,653Kbps download and 1,090Kbps upload on the iPhone 4. Overall, on the AT&T network, on average, the iPhone 4S is about 10 percent faster than the iPhone 4 in terms of data connection.
And the winner is...
Unlike the AT&T phone, Sprint's iPhone 4S had no problems with reception at CNET's offices. Its data speeds were also more reliable, ranging from 735Kbps to 1,965Kbps down and 321Kbps to 983Kbps up at different locations. Though some Sprint iPhone 4S owners have reported significantly slower data speeds, we haven't seen such a change.
The most consistent, however, was the iPhone 4S from Verizon, which averaged between 870Kbps and 988Kbps down and between 605Kbps and 707Kbps up throughout the city. The connection speeds of Verizon's and Sprint's iPhone 4Ses, while slower even than those of AT&T's iPhone 4, also seemed to be consistent with what the carrier said the devices would offer.
Note that these test results showed that AT&T's iPhone 4S was faster than those of Verizon and Sprint, which is not in line with what CNET editor Kent German found in his full review of the iPhone 4S. However, Kent tested the phones only at the CNET office, and it's also worth mentioning again that you might get different cellular data rates when testing the same device at different times.
Despite all the differences, the numbers showed that the iPhone 4S' data connection, when you can get a 3G connection, is fast enough for most regular Internet needs. In my trials, e-mails came quickly enough, and Google Maps, for the most part, loaded instantly in real time.
On the other hand, it's not fast enough to make watching streaming videos, such as YouTube, a pleasant experience. I was streaming the same video clips on the phones when moving around the city and none was able to play any of the videos without periodically pausing to rebuffer.
My tests also showed that it is disappointing, though not entirely surprising, that the iPhone 4S doesn't support 4G as many had hoped. As expected, the iPhone 4Ses are in no way offering data speeds close to those of a 4G device. The T-Mobile Sonic 4G Mobile HotSpot, which was included in the testing, was one of the slower 4G devices I've seen but still averaged around 3,028Kbps for download and 1,205Kbps for upload, significantly faster than any of the iPhone 4Ses.
So the conclusion is that if you're looking to improve your mobile Internet access and already have an iPhone 4, you should probably skip the iPhone 4S, as it won't make much of a difference. You'll miss out on Siri's soothing voice for now, but she'll most definitely still be there with the next version of the iPhone, which will, hopefully and likely, support 4G. After all, most of her answers require a good connection to the Internet anyway.