But as we saw in the first of this multi-part series on 4G and its impact on the enterprise, Xohm is not, strictly speaking, 4G.
Many use the term loosely to include today's WiMAX, but as analyst Phillip Redman, a research vice president at Gartner, points out, the International Telecom Union (ITU), a United Nations agency, will define 4G, as it did 3G. And it hasn't done that yet.
The ITU's standards-setting process has barely begun. However, it has set objectives. They include delivering orders of magnitude more bandwidth than current-generation WiMAX. So in that respect alone, Xohm is clearly not 4G, Redman argues.
The Institute of Electrical and Electronics Engineers (IEEE), the standards body behind the current WiMAX technology that Xohm uses, 802.16e, is developing a next-generation standard that will meet the ITU objectives.
But as we also saw last time, most observers are picking LTE (Long Term Evolution), a technology being developed by the 3rd Generation Partnership Project (3GPP), as the dominant 4G technology, at least in the developed world, at least among established mobile operators.
So Sprint, by adopting WiMAX, is definitely going against the 4G current.
Xohm is also not a fully mature 4G service in one other important respect. Although subscribers are free to use voice over Internet (VoIP) services such as Skype when connected to the networksomething 3G operators often block - there is no conventional voice component to Xohm.
It's a data-only service, and intended as such. At least for now. In fact, Sprint and Clearwire are targeting the residential fixed broadband Internet access market as much as the mobile data market.
All this being said, the fact remains that Xohm is out there nowa good two years ahead of the first expected LTE deployments. It's fast, it's mobile. And it's a serious play. The two main partners, as well as others, including Intel, have invested billions.
If nothing else, Xohm's progress should offer useful insights into how 4G might play out in the longer term, and how it could impact users.
But it's still early days. Baltimore was the only Xohm market officially up and running at the time of writing, and even it is not entirely covered.
As of late October, only 180 of an eventual 370 cell sites had been builtalthough Sprint vice president of broadband Bin Shen says the company is "expanding pretty rapidly." Eventually the network will cover 70% of the Baltimore population, or about 1.4 million.
How will the build-out proceed after Baltimore? On the big picture, Shen will say that the company hopes to have 60 to 80 million in population covered by the end of 2009, 140 million by the end of 2010 and 200 million by the end of 2012.
Chicago and D.C. have been tagged as the markets it will launch next. It already has 500 cell sites in place in Chicago, Shen says. "We'll be in position to launch very soon. It's just a matter of making sure we can deliver great performance and have sufficient coverage."