On the funding side, LightSquared is likely to need multiple billions of dollars to build out its planned network, and it hasn't raised anywhere near that amount so far.

Establishing a nationwide 4G network is no easy feat in any case. WiMax operator Clearwire has spent at least $6 billion in developing its 71-market WiMax network, and it is .

One recent rumor suggested that LightSquared would sign a deal with Sprint to use Sprint's tower infrastructure to help with its buildout costs. Another rumor floated the prospect of a LightSquared IPO to raise money via the public markets. Both avenues are certainly possible, but each carries risks and conditions that may stall or complicate LightSquared's ambitious plans.

Being a wholesale operator, LightSquared will face tough but indirect competition in the marketplace from Verizon Wireless and AT&T, which is in the midst of a push to gain regulatory approval for acquiring T-Mobile USA, .

Another key question about LightSquared is whether device makers will support the network. If Best Buy decides to sell a phone that runs on LightSquared's network, a phone maker must agree to design and bake a LightSquared radio chip into the device.