Today Softbank — whose assets include the third largest mobile carrier in Japan — announced its intent to purchase a 70% share of Sprint in a complex financial transaction. It's a gutsy move by a company that has proven success as a market disruptor, first in fixed broadband service and more recently in mobility. Assuming the deal passes regulatory and shareholder muster, Sprint will receive a massive cash infusion that will expedite its implementation of its Network Vision update and its deployment of LTE technology across its national footprint.

But for Sprint to have any realistic chance of wresting market share from the Verizon and AT&T behemoths, it requires additional spectrum to expand its LTE capacity beyond the puny 5×5 MHz of its current plan. And there's a carrier rich in that spectrum resource: Clearwire. Sprint holds a minority interest in Clearwire, some of its customers use Clearwire's network, and it has designed support for the company's spectrum into its Network Vision, but Clearwire needs capital to complete its network and to effect the network's transition from WiMAX to LTE.

If Softbank's president Masayoshi Son is serious about enabling Sprint to disrupt the US mobile market, he needs to add control of Clearwire to his shopping list. CIOs looking to exploit Sprint as a viable alternative to the Verizon-AT&T duopoly need to see this additional step on the roadmap before making a commitment to Sprint for the long-term future.