Watch out, Verizon, AT&T!, says Softbank CEO

Sprint's Son: Wireless network in US is horrible

Masayoshi Son, the founder, Chairman and CEO of Softbank is not a man who backs away from a fight. He has famously taken on the incumbents in Japan's wireless and broadband business and emerged victorious both times. It's his hope to do the same here in the U.S., as the company he controls, Sprint (80 percent owned by Softbank) competes against what he routinely calls the "duopoly" of Verizon and AT&T.

But to compete in the way he hopes to, Sprint needs scale. In a wide ranging interview, Japan's richest man made it clear that without that scale, Sprint will not be able to bring American consumers the far higher level of speed that Son says can be delivered to wireless devices today, not to mention the price competition that he maintains is lacking in the U.S. wireless market.

Masayoshi Son, chairman and chief executive officer of SoftBank Corp.
Tomohiro Ohsumi | Bloomberg | Getty Images

While Son did not specifically address whether he hopes Sprint will merge with or acquire T-Mobile, it is clear that is the deal that will give Softbank the scale Son says it needs in order to invest more confidently and quickly in its U.S. wireless business. Without that scale, Son said it will be a "long shot" for Sprint to compete effectively with Verizon and AT&T and upgrade a level of U.S. wireless service he terms "horrible".

In addition to Sprint, Softbank controls 37.6 percent of Alibaba, the enormous Chinese e-commerce company that is expected to go public this year. Son said he will welcome a public Alibaba, though Softbank will not be selling into the IPO. And when questioned on whether the company can continue to grow at its current pace, Son said that Alibaba "has a lot of things cooking." While Son reserved his highest praise for the late Steve Jobs, as the single biggest customer of Apple's worldwide, he also said that Apple CEO Tim Cook is the best man to have taken the helm of the company after Jobs' passing.

—By CNBC's David Faber. Follow him on Twitter @davidfaber.