Sprint Nextel apparently is debating whether to let T-Mobile USA invest in Clearwire Corp., the company Sprint Nextel has a 54-percent majority control of, and which is the foundation for Sprint's fourth-generation network. There does not appear to be a specific offer from T-Mobile USA, but the company has to figure out some strategy for getting to 4G without buying spectrum. An investment in Clearwire would provide a solution.

But why would Sprint consider enabling a competitor? At least part of the reason for the discussions are Clearwire's need for additional investment capital to complete its national network build. 

Clearwire needs new funding by the end of the year and is in talks with new and existing customers about an expansion of its footprint in the United States. If T-Mobile USA invests in Clearwire, depending on the extent of the investment, Clearwire would gain needed cash.

On the other hand, that "solves" T-Mobile USA's 4G network problem, presenting Sprint with a better-placed competitor. 

The discussions necessarily raise questions about the strategic value of network ownership, versus leasing of capacity; the relative value of network operations compared to marketing investments; as well as the value and structure of business partnerships. 

Clearwire long has said it would operate both as a wholesale and retail entity. In fact, Sprint and several cable operators are Clearwire's most-significant wholesale customers, and there is at least some sense in which each of the wholesale partners competes with Clearwire for retail end users. 

It is of course one thing to sell capacity and services to non-direct or minor competitors, and perhaps quite a different matter to enable a key or major competitor. Beyond that, there are additional issues.

Sprint might consider the spectrum and network assets valuable enough to want to acquire all of Clearwire. Sprint might also conclude that the challenges of managing an enterprise with significant minority partners are additional reasons to want sole ownership. 

On the other hand, some might argue majority control, without full ownership, provides most of the benefit at lower cost, at a time when there are competing and alternative uses for capital or operating investment.

Any decision will be complex.