As the market in general has shot steadily upward over the last 12 months, shares of telecom giant AT&T (NYSE:T)  have largely disappointed. And by "disappointed," I mean gone virtually nowhere. 

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Investors are understandably hopeful AT&T will break out of its recent funk when it reports its Q4 2013 quarterly earnings on Jan 28. Problem is that this might be wishful thinking for AT&T.

AT&T under pressure
It'll be interesting to see whether AT&T falls victim to what's been perhaps the single greatest theme at work in the U.S. telecom market over the last two years: renewed competition.

Although it wasn't clear by any means then, the impact of U.S. Department of Justice's decision to veto AT&T's attempt to acquire T-Mobile in late 2011 is hard to overstate today. It marked a turning point, which has since seen the resurgence of once-irrelevant players Sprint Nextel and T-Mobile, albeit for very different reasons. Now both parties, but especially T-Mobile, have taken direct aim at the larger incumbents in the U.S. telecom market.

In the video below, tech and telecom analyst Andrew Tonner looks at some of the key numbers and issues investors should be on the lookout for when AT&T reports on Tuesday.