Let's say you're a large American cellular carrier, and you know what 4G means, because there's an international standard that defines it. Let's say your current network doesn't comply with that standard so you call it something else more accurate. Now let's say your competitors' networks are slower than yours but they use the term 4G anyway.
What would you do?
Well, according to this rumor/story from Android and Me, if you're T-Mobile, you'll call your network HSPA+ and say you can "deliver 4G speeds." You can't actually do that, because those speeds are defined as "target peak data rates of up to approximately 100 Mbps" for mobile devices, but nobody in the mobile business anywhere is delivering those speeds either.
Your speeds of 21 Mbps are faster than any of the other US mobile carriers' data rates. So given that fact, then you'll finally get disgusted and let everyone know if those other no-good rotten lying carriers don't stop calling themselves 4G, why, why...you'll call your network 4G too. So there!!!
The ITU-R, the international standards body for mobile communications (among other things), looked at six of the newer wireless technologies out there and said only two of them could be called 4G: WiMax 2, and Long Term Evolution Advanced. Nobody is using those technologies yet. Sprint is using Clearwire WiMax (10 Mbps) and Verizon is rolling out its LTE (not LTE Advanced) network. Both call their networks 4G, and neither delivers the speeds or the standards. Supposedly they don't even meet 3G standards because neither Sprint nor Verizon can handle voice and data simultaneously. (Yes, they're working on solutions, but right now they don't meet that voice/data requirement of 3G.)
Supposedly nobody in the US is going to meet these 4G standards until the year 2013. But that isn't stopping Sprint and Verizon from using that term 4G now. So what's T-Mobile going to do?
Big Magenta has been calling their network HSPA+, which stands for High Speed Packet Access Plus, also known as Evolved HSPA. It's a 3GPP standard, which contains the term "3G." And everyone knows 4G is one more G than 3G, so who cares about HSPA+? The customer wants more Gs in his phone, and the customer is always right. Also HSPA+ doesn't have any Gs, so how can it be any good?
T-Mobile will do a Find-and-Replace on their marketing documentation, HPSA+ out, 4G in. Introducing a new phone called the myTouch 4G fits right into that plan. If the customer wants more Gs, then T-Mobile says put them right on the phone.
Source: Android and Me