Sprint will work with fellow WiMax provider Clearwire on building its national "4G" network, the two companies said on Thursday.

The deal includes a roaming agreement between the two companies, and will lessen the strain on Sprint to quickly cover a large portion of the country. Sprint will focus on major markets, while Clearwire will build out in the smaller ones.

Clearwire will also gain access to Sprint's EV-DO network as part of the agreement, allowing it to offer data access in areas not yet covered by WiMax.

Both companies will work together on the service aspect, as well as branding and marketing. Where needed, the companies will exchange 2.5GHz spectrum to speed the build-out of the network.

"Our companies share a vision of doing for the Internet what cellular and PCS networks did for voice communications starting more than twenty years ago," Clearwire CEO Ben Wolff said in a statement. "Based on this shared vision and the expected benefits to each company and our respective shareholders and customers, it is natural that we would work together."

Clearwire's deal with Sprint is its second major pact in as many months. In June It signed a deal with both DirecTV and Echostar to allow the companies to resell high-speed Internet access. Around that same time, rumors surfaced of talks between the two companies.

Sprint plans to spend as much as $3 billion to roll out its WiMax network, which has been met with some resistance by investors. The carrier has been losing both money and customers as of late, and many believe WiMax is a huge risk for the company.

The Department of Justice must still approve the deal, which is for 20 years, with 10-year renewals. The FCC would also need to approve any possible transfers of spectrum.