After having spent billions of dollars in rolling out new super-fast 4G networks for browsing the Web on mobile handsets, bigwig US wireless providers - Verizon, AT&T and Sprint - now face the first real test for their respective 4G technology --- the launch of the iPhone 5!

With 4G technology marking the fourth major upgrade of the carriers' networks since the commercial rollout of cellphones thirty years back, the technology has been heavily marketed by the carriers, despite the fact that the 4G networks of AT&T and Sprint are nowhere close to completion as yet.

While the 4G networks are currently been used by just a small percentage of cellphone users, there could be problems in the offing for the carriers after the LTE-capable iPhone 5 is launched.

Since iPhone 5 may persuade users to try out the 4G networks of their service providers, the gaps in the three carriers' 4G coverage will apparently be exposed; thereby underscoring a truly testing time for the networks' ability of dealing with heavy traffic for the first time.

With the population of the US being approximately 312 million, there are chances of the carriers stumbling in the face of increasing use of 4G networks by consumers --- more so as Verizon's LTE network covers a population of 230 million, but with gaps in rural and certain suburban areas; AT&T's network covers only around 74 million people; and Sprint's network is presently available in just 19 cities!