While Clearwire has talked about extending the service to major U.S. cities, it isn't clear what its rollout plans are, especially because the company is now saddled with debt and financial markets are in crisis.

Another problem is a shortage of devices subscribers can use. While Intel is betting laptop makers will include WiMAX capability soon in a number of their products, there are few on the market now. Most laptop users will for the time being buy plug-in modems. Nor are there any WiMAX-equipped cellphones available in North America. In fact Nokia just decided to stop selling the N810 WiMax mini computer it offers through Xohm.

Allen is clearly rooting for Clearwire to expand fast. "It doesn't make a lot of sense to me for them to be unexpansive" having secured some US$3.2 billion in investments from Intel, Google and cable operators Comcast and Time Warner Cable.

Why, he asked, would Clearwire want to "sit on their hands while their lead erodes over other technologies," such as LTE.

"I'm not seeing anything in my interaction with them that tells me they're slowing down."