AT&T today said it is selling off former BellSouth broadband wireless spectrum in the Southeast to Clearwire, which is currently deploying a wireless broadband network piece-by-piece across the country that it eventually plans to upgrade to WiMAX.

AT&T will unload the 2.5 GHz spectrum, which matches the current license holdings Clearwire has in other regions of the U.S., for $300 million in cash. Though AT&T and the other RBOCs hold 2.5 GHz licenses in their local operating territories across the U.S., the vast majority of the spectrum is owned or leased by Sprint and Clearwire, making them the only operators capable of deploying nationwide networks over the frequencies. Sprint is currently deploying a Mobile WiMAX network using Motorola, Samsung and Nokia technology, starting in Chicago and Washington, D.C. and expanding across the country from there. Clearwire opted to use proprietary technology developed by its subsidiary NextNet, but last year it sold the infrastructure vendor to Motorola and agreed to migrate its networks to WiMAX.

Though AT&T is giving up spectrum that is currently targeted for WiMAX it has other broadband wireless spectrum, including Wireless Communications Services (WCS) spectrum, which BellSouth used to launch several wireless access trials in the Southeast. AT&T is conducting its own trials using WiMAX and other pre-WiMAX and proprietary technologies in different markets across the country. The most significant of those launches is in Pahrump, Nev., where AT&T has rolled out a commercial network over WCS bands using Mobile WiMAX technology from Soma Networks.

The deal will close promptly after the company gets the proper government approvals, AT&T officials said. Clearwire will not only receive Broadband Radio Spectrum (BRS) at 2.5 GHz which AT&T owns the licenses to outright, but it will also get Education Broadband Service (EBS) spectrum, which is owned by educational and non-profit organizations that had leased their spectrum to BellSouth.