Legendary fund manager Peter Lynch once said that you shouldn't invest in any idea you couldn't illustrate with a crayon.

Though I'm not much for crayons, I do love the pithiness of that line. We regularly preach the same idea at the Fool: Don't buy what you don't understand. And if you can't simply sketch out a company's business model -- how it actually makes money -- then maybe you shouldn't be investing in it.

Frontier Communications (Nasdaq: FTR) has been making something of a comeback recently -- particularly after last week's earning report. Let's take a look at where Frontier is focusing its efforts, and where opportunity for expansion might still remain. (Note: I'm focusing on subscribers here, not earnings.)

Ftr

Source: Frontier Communications' 2011 10-K.

Think I missed something in this illustration? General thoughts on this exercise? Let me know in the comments section below. And if you haven't already, be sure to read our premium research report on Frontier Communications; we walk you through all of the key opportunities and threats facing the company. Better yet, you'll receive a full year of updates to boot. Click here to learn more.