Ultra mobile broadband is held up as the shining successor to evolution-data optimized, the 4G answer for CDMA operators that set them down the path to true high-capacity networks. The numbers are impressive: 280 Mb/s over a 20 MHz channel as opposed to the roughly 45 Mb/s of capacity available over the same spectrum with EV-DO networks.

But UMB is a disruptive technology, the first interruption in an unbroken chain that has kept CDMA operators on an upgrade path since the late '90s. It's not even a CDMA technology. UMB uses orthogonal frequency division multiplexing (OFDM) on the downlink. New, larger channel sizes also will require new spectrum. If CDMA operators want to pursue the technology standards path they've been following for more than a decade, they'll have to build new networks.

Though carriers aren't balking at the idea of new network construction, many of them are exploring their options. Unbound for the first time by an obvious network migration path, CDMA operators are looking to other technologies: WiMAX and even the long-term evolution (LTE) technology being developed by their arch-nemesis in the technology wars, the GSM community.

So far it's only Sprint that's strayed from the Third Generation Partnership Project's 4G evolution path. But the defection of one of the world's largest technology carriers to WiMAX has emboldened non-CDMA vendors, which now think they have a chance of coaxing CDMA carriers to the other side. The technology wars may be about to begin again.

NEXT PAGE: Neither Sprint nor Verizon Wireless have made any firm commitment to pursuing UMB...