Sprint's LTE plans sounded pretty good to me when I listened in to its presentation this morning. It will free the company from its oft-testy relationship with Clearwire, put its 1.9 GHz spectrum to good use and give it additional ammo against AT&T and Verizon Wireless.

Clearly, I'm not an investor. Sprint's stock went into free fall this afternoon, shedding more than 13 percent.

I was only able to listen to about a third of the event, which lasted for nearly three hours. Listening to a replay of the parts of the announcement I missed – especially the question and answer session at the end – I can see why investors were less than satisfied with Sprint’s plans.

For months, Sprint had promised to deliver answers at today's strategy update. Instead, it delivered generalities that left questions about its finances and strategy unanswered. Here's a description from BTIG Research analyst Walter Piecyck:

"After a slate of presentations that were far short on details, the Q&A session got ugly as the management team continued to avoid providing any detailed answers and in many cases offered responses so short and void of details that the CFO was actually laughed at.  By the end, the CTO arrogantly admonished a questioner to “get your facts straight” rather than provide a detailed explanation of a plan that, when described as “ridiculous”, received applause from the audience.”

Ouch.

Sprint's decision to build its own LTE network instead of relying on Clearwire leaves the WiMAX operator in the lurch, and the impact of that could have unpleasant repercussions for Sprint. Since Sprint is Clearwire's majority shareholder - and is (or should I say was) its largest customer - any damage to Clearwire could harm Sprint as well. Maybe that’s not such a good idea.

Then there is the little matter of spectrum. Repurposing its 1.9 GHz spectrum for LTE is a nice idea, but will the network be speedy enough and launch fast enough to effectively compete with Verizon and AT&T?

Sprint is deploying LTE in its G block spectrum, giving it just 10 MHz to work with – half the bandwidth Verizon is using for its LTE network. Sure, Sprint will add additional capacity from its 1.9 GHz holdings as it phases out its iDEN network, but whether it can compete with LTE networks using more spectrum in prime 700 MHz real estate is another matter entirely.

Piecyck, for one, has his doubts.

“There was no discussion on how these speeds would stack up against Verizon and AT&T, which are using twice the amount of spectrum, nor how much capacity they would provide until they need to free up more spectrum,” he says. “However, they didn’t lose a chance to mention that their speeds would be faster than WiMAX.  We look forward to testing that claim.”

Sprint may end up deploying an LTE network that is slower and later to the game than its top two competitors. Not good.

Then there’s the little matter of financing.

CFO Joe Euteneuer threw out some rosy numbers about the impact of the plan on Sprint’s profit margins, but they came with some fine print. His estimates excluded the impact of the iPhone. That’s sort of like calculating your monthly budget without counting your mortgage payment. Sprint will have to “go to the market for financing” – i.e. go into more debt – to pay for its new network, the supposed financial benefits of which don’t include the massive cost of the estimated 30 million smartphones it just bought from Apple.

I’m starting to understand why investors are feeling a bit disgruntled.

As if you needed more to think about, LightSquared’s involvement in Sprint’s plan provides another twist in the operator’s increasingly complex 4G plot. Sprint might be able to use LightSquared’s 1.6 GHz spectrum, or it might not, depending on whether the FCC gives LightSquared the go-ahead before the end of the year.

Clear as mud.

In the meantime, Sprint is moving ahead with construction of its LTE network – will it incorporate the LightSquared component at a later date? Will it exercise its right to nix the deal if LightSquared doesn’t get the green light by Dec. 31? I don’t know, investors don’t know. Does Sprint even know?

I still like the idea of Sprint building its own LTE network. I like that it is replacing its iDEN network with a CDMA-based push-to-talk service. But like Sprint’s investors, I want more information about its plans. Sprint was supposed to give us answers today, but left us with questions.