If AT&T's marketing of the iPhone 4S as a 4G phone has left you scratching your head in confusion, you're not alone.

AT&T has ramped up its marketing efforts lately, airing commercials on TV that highlight the iPhone 4S as a 4G device. The TV ads emphasize that AT&T's version of the iPhone 4S can download Web content three times faster than its competitors because it's operating on AT&T's 4G network. While technically the iPhone 4S on AT&T may be faster than the same device on Verizon and Sprint, is it really a 4G device? In this edition of Ask Maggie I try to clear up the confusion.

Deceptive advertising by AT&T?

Dear Maggie,

While watching TV this morning I saw an ad for the iPhone 4S on the AT&T network. As you can see from the attached screenshot, AT&T is claiming that their 4G network makes downloads faster on the iPhone 4S. I was under the impression that the iPhone 4S is a 3G phone on all carriers. Kent German backed this up in his review of the phone.

Isn't this deceptive advertising by AT&T? The advertisement paints a picture that the iPhone 4S on AT&T is running on a 4G network.

What do you think?

Thanks,

Frank

Dear Frank,

Let me start by saying that I agree with you. I think that AT&T is confusing customers by calling the iPhone 4S a 4G phone. The device runs on AT&T's HSPA+ network, which is merely an upgrade to its traditional 3G network. That said, AT&T's claim that the iPhone 4S uses technology that is three times faster than its traditional 3G network, is true.

CNET/Josh Lowensohn

But it's still way slower than the 4G LTE network that the new iPad uses. It's also considerably slower than even more advanced versions of HSPA+. The iPhone 4S supports 14.4 Mbps HSPA+. Meanwhile, there are two faster versions of HSPA+ that offer theoretical network download speeds of 21 Mbps and 42 Mbps.

In other words, the iPhone 4S offers a slight speed boost over the iPhone 4 and other 3G devices. But I wouldn't say it's significant enough to put it in the same class as devices operating on a 4G LTE network or even devices operating on the newest and fastest versions of HSPA+.

But is AT&T's 4G claim for the iPhone 4S deceptive in the legal sense? Not really. The short answer to your question is that 4G is merely a marketing term. It's like calling Vitamin Water a health food. Marketers are allowed to call it whatever they want, but the truth is that Vitamin Water is full of sugar, which isn't all that healthy. And AT&T's HSPA+ version of 4G is also not what I or most other experts would consider true 4G.

I think it's unfortunate that AT&T has chosen to market the iPhone 4S in this way, since it's confusing for consumers. And it will likely only get more confusing as AT&T rolls out its 4G LTE network. This is the technology currently supported in the new iPad. And it's likely to be supported in the next version of the iPhone, which I expect will be introduced later this year.

Will the real 4G please stand up?

So what technologies are considered 4G? LTE or Long Term Evolution is what most experts consider 4G. Another technology called WiMax has also traditionally been called 4G. Sprint Nextel and Clearwire have built a 4G network using WiMax. Verizon and AT&T are building LTE networks. And Sprint and T-Mobile now have plans to build LTE networks.

The reason that LTE and WiMax have been considered 4G is that they are based on a new type of network technology that is more efficient than previous 3G technologies. LTE and WiMax use what's called orthogonal frequency-division multiple access or OFDMA modulation.

LTE and WiMax also differ from traditional cell phone technology because these networks are exclusively data-centric. While traditional cellular networks, have a separate voice network, WiMax and LTE will offer voice service over the data network, much like VoIP services like Skype or Vonage operate on a traditional broadband network. Treating voice as just another data application on the network allows for more efficient use of the wireless spectrum and network resources. And this is a big reason why carriers are switching to these "4G" network technologies.

But 4G wireless technologies are also supposed to bring much faster upload and download speeds to the network. LTE, WiMax and even HSPA+ all offer faster speeds. But the truth is that none of them live up to the official definition that has been established by the International Telecommunications Union, an international telecom standards setting body within the United Nations.

According to the ITU's IMT-Advanced specification, for a technology to be considered "4G" it must deliver downlink speeds of 1Gbps when stationary and 100Mbps when mobile. So far no commercialized standard -- whether it's WiMax, LTE or HSPA+ -- has even come close to reaching these aggressive specifications.

Today's WiMax standard has the potential to achieve theoretical downloads of 40 Mbps. And LTE can achieve speeds of 100 Mbps. There are updates to each of these standards coming. And WiMax 2 and LTE-Advanced are expected to get these technologies closer to the ITU's 4G spec. HSPA+, which doesn't use OFDMA, is also advancing and may one day achieve the ITU's 4G limits.

Still, even though neither WiMax nor LTE is able to meet the ITU's strict speed requirements, up until a couple of years ago when experts talked about 4G, they were talking about networks built on WiMax and LTE. And networks using HSPA+, which uses the same infrastructure as traditional 3G networks, was not considered 4G.

But as Verizon and Sprint began marketing their 4G networks, T-Mobile USA, the smallest of the four nationwide carriers, renamed its 3G HSPA+ network 4G to keep up with the big boys.

T-Mobile had been late to the 3G market. And at the time, the company had no plan to eventually upgrade to LTE technology. Instead, it began aggressively upgrading its to more advanced HSPA+. In markets where it deployed 21 Mbps HSPA+, download speeds are actually faster than what can be achieved with Sprint's 4G WiMax service. T-Mobile has even upgraded further, and now some portions of its network support 42 Mbps HSPA+.

When T-Mobile first started marketing HSPA+ as 4G, AT&T, which was also upgrading to HSPA+, criticized the company and said the carrier's loose terminology would confuse customers. But within the year, AT&T, which also began upgrading its traditional 3G HSPA network to faster versions of HSPA+, also started calling its service 4G.

AT&T's change of heart may have had something to do with the fact that the ITU softened its stance on the 4G nomenclature. The group back-pedaled from its hardline 4G specs and issued a statement declaring that the 4G moniker "may also be applied to the forerunners of these technologies, LTE and WiMAX, and to other evolved 3G technologies providing a substantial level of improvement in performance and capabilities with respect to the initial third generation systems now deployed."

Even though the ITU has no real authority to police carriers for what name they call their networks, the ITU's declaration opened the door for AT&T and T-Mobile to justify their marketing campaigns.

AT&T had already begun marketing some of its HSPA+ devices as 4G prior to the iPhone 4S launch. But when that device came out last October, AT&T ramped up its marketing machine and really pushed the iPhone as 4G.

It's hard to prove that AT&T is actively trying to deceive its customers into thinking that the iPhone 4S is using the same type of 4G technology as a 4G LTE device from Verizon. So I won't go that far. But I do find it hard to believe that AT&T wouldn't at least think that its marketing strategy could confuse customers. And even though it considers all of its HSPA+ devices "4G," AT&T has paid particular attention to making the distinction with the iPhone 4S. For example, after the recent iOS update, a new "4G" icon appeared on AT&T iPhone 4S's to indicate which network it was operating on. This "4G" icon does not appear on iPhones operating on HSPA+ networks overseas. What's more, AT&T offers other HSPA+ devices, and the network indicators on some of these devices don't get the "4G" indicator when they're detecting an HSPA+ signal.

My guess is that at the very least AT&T wants to point out that its version of the iPhone 4S is superior to other versions of the same device being sold on Verizon's and Sprint's networks. In fairness to AT&T, there is a difference between the GSM version of the device and the CDMA version sold by Verizon and Sprint. HSPA+, even the 14.4 Mbps flavor, is faster than the 3G EV-DO technology on Verizon and Sprint.

That said, I wouldn't say that the version of HSPA+ that AT&T supports on the iPhone 4S always results in a noticeably faster experience when compared to a CDMA iPhone 4S. But it is a technical difference. And my guess is that AT&T, which for the first time was not the exclusive carrier for a new version of the iPhone when it launched, needed to highlight a difference to set itself apart from the competition.

Like you, I find the whole situation frustrating and misleading. And honestly, as an AT&T customer, it bothers me. Most consumers haven't followed the whole 4G naming saga as closely as I have. And as a result, even people who bought the iPhone 4S last year thinking it was then a 3G phone, now are suddenly wondering if it's magically become a 4G device.

The problem is only getting worse as AT&T pushes its new 4G LTE network. And now AT&T must split hairs to differentiate between its HSPA+ 4G and its LTE 4G networks. Not only are there huge differences in performance, which result in vastly different expectations, but AT&T treats 3G and 4G users on its unlimited plan differently. AT&T HSPA+ subscribers with an unlimited plan can use up to 3GB of data for $30 a month. This is the same for 3G unlimited users. But 4G LTE customers get up to 5GB of data per month for the same price.

In other words, when it's convenient for AT&T to call HSPA+ devices, such as the iPhone 4S, 4G, it does so. But when it's not, it applies 3G pricing and restrictions to those same customers.

The good news is that I expect the new iPhone when it's introduced will support LTE. And then iPhone users will truly get a taste of what 4G is really about.

Ask Maggie is an advice column that answers readers' wireless and broadband questions. The column now appears twice a week on CNET offering readers a double dosage of Ask Maggie's advice. If you have a question, I'd love to hear from you. Please send me an e-mail at maggie dot reardon at cbs dot com. And please put "Ask Maggie" in the subject header. You can also follow me on Facebook on my Ask Maggie page.