Telecommunications companies plan to announce on Wednesday that it intends to build the first of a new generation of nationwide wireless data networks, according to several people briefed on the deal. The consortium includes a disparate group of partners: Sprint Nextel, Google, Intel, Comcast, Time Warner and Clearwire. The partners have put the value of the deal at $12 billion, a figure that includes radio spectrum and equipment provided by Sprint Nextel and Clearwire, and $3.2 billion from the others involved. They expect the network, which will provide the next generation of high-speed Internet access for cell phone users, to be built in as little as two years, but there is no timetable on when it will be available to users and the price is not determined. The partners are seeking to beat Verizon Wireless and AT&T Wireless to the market. The partnership of such fundamentally different companies underscores the convergence of Internet, entertainment and telecommunications services. The wireless network of the future is expected to be fast enough — rivaling speeds that cable customers have in their homes today — to allow delivery not just of text and simple Web pages, but of video and advertising.