Qualcomm has racked up another huge win for its Forward Link Only mobile TV technology, announcing on Monday that AT&T has selected its MediaFLO USA subsidiary as the provider of multi-channel broadcast TV service for Cingular.

Coupled with its previous Verizon Wireless deal, the agreement makes FLO the mobile TV technology for the two largest providers in the U.S., which combined serve more than 120 million subscribers. That doesn’t paint a rosy picture for FLO’s competitive technology, Digital Video Broadcast-Handheld (DVB-H), which has yet to launch in the U.S.

Two service providers, Modeo and Hi-Wire, are launching DVB-H networks. Modeo, owned by tower company Crown Castle, has a live network up in New York, but the service is still in beta trials with limited users since Modeo hasn’t landed a carrier commitment. And Hi-Wire, a company formed by 700 MHz spectrum winner Aloha Partners, has just launched its first trial network in Las Vegas. Though both T-Mobile and Sprint have yet to commit to a service provider, the MediaFLO deals with their competitors puts pressure on the two carriers to launch TV services soon with whatever technology is currently available.

Verizon Wireless is launching its TV service by the end of the quarter, but the other carriers will get a slight reprieve from Cingular. Its planned launch is before the end of 2007, which will give DVB-H providers a bigger window to build out their networks.

For AT&T the deal lends credence to the three-screen strategy it has been pushing since its merger with SBC Communications. After acquiring BellSouth, it gained full control of wireless joint venture Cingular, which it is now branded the “New AT&T.” Except for some smaller deals with Yahoo to extend services between DSL and the mobile deck, there has been to no continuity between the services of the mobile and wireline divisions of the company. The MediaFLO deal will allow AT&T to offer the exact same content on specific channels over both the phone and its fiber TV service. Some channels like MTV will be simulcast over the phone and set-top box simultaneously.

Meanwhile MediaFLO continues to fill up its channels. It announced deals with CBS, NBC, Fox, MTV, Comedy Central and Nickelodeon at its launch last month, and last week signed up ESPN to a channel.