In practice, this means that anyone using LTE, WiMAX, or HSPA+ today is using "4G." All of these networks deliver far more megabits per second than most existing, older 3G networks. Some of them are doing so by using some of the technologies that will eventually appear in LTE-Advanced and WiMAX2. For the carriers, this is enough to qualify as 4G for marketing purposes.
So who has the most 4G coverage? It depends.
If you're asking about LTE, it's generally accepted that Verizon has by far the largest number of locations with LTE service. On Nov. 15, the carrier announced it has LTE in 440 U.S. markets or cities, faster than originally planned. It expects to complete its initial LTE build out by mid-2013.
A distant No. 2 right now is AT&T, which claims 103. Third of the Big Four is Sprint, which began rolling out LTE in June: it's now in 32 cities.
But these numbers change weekly, sometimes daily. Eighteen months from now, at least in the major markets, there will be little difference in the size of the LTE blankets offered by the Big Four carriers. And there are regional carriers with expanding LTE service: MetroPCS, which was actually the first to go live with LTE, and U.S. Cellular, are examples.
AT&T doesn't claim to have the biggest LTE network, but it does claim to have the biggest "4G" network - a network that includes two cellular technologies: LTE and HSPA+, which now overlays its older nation-wide 3G network. AT&T adds its LTE locations and its HSPA+ locations to say it offers "4G" in 2,000 more locations than Verizon today offers LTE.
T-Mobile doesn't claim to have the biggest 4G network, but it does claim to have the fastest. The carrier has aggressively invested in HSPA+, continually upgrading to faster and faster flavors, most recently the highest performing 42Mbps flavor. And just as aggressively it markets this as 4G.
Tests by PC Magazine, and most recently RootMetrics, show T-Mobile's HSPA+ network often overlaps and sometimes beats Verizon's LTE download performance, though Verizon can far more often top 15Mbps. Via email, T-Mobile says its "nationwide 4G" network is available in 229 markets, reaching well over 220 million potential customers; HSPA+ 42 service is a subset of that coverage: it's in 185 markets, with 184 million potential customers, and growing.
The term "most coverage" is often wrongly understood or interpreted as "best coverage." Either way, it's an irrelevant metric to the vast majority of subscribers. "Ninety percent of the people stay 90% of the time in the same place," Entner says.