But Clearwire claimed some momentum for WiMax, too. Its statement on Wednesday pointed out that the WiMax Forum industry group says WiMax service providers around the world reach 430 million people today. By the end of next year, the group expects 800 million people to be in range of a WiMax service. WiMax is based on IEEE 802.16, a family of open standards.

The Clearwire joint venture came to life last November when the combination of Sprint Nextel and the national pre-WiMax service provider Clearwire was finally completed. The company, which eventually will sell service on both Sprint-built and Clearwire-built networks under the Clear brand, is also backed by partners including Intel, Google and some of the largest U.S. cable operators. Together, those companies injected US$3.2 billion into the venture.

But amid Sprint's business woes, the declining economy and tight credit markets, Clearwire is in a tough environment for building out a national network with a new technology. Intel and other major partners recently took charges against their financial results for a decline in the value of their Clearwire investments. Clearwire said Wednesday it has enough capital to cover its rollout well into the future.