AT&T (NYSE: T) is activating more iPhones, but Verizon (NYSE: VZ) is growing its wireless revenue three times as fast as its closest rival.

And investors don't seem to care. The stock is trading marginally lower because Big Red didn't blow away Street expectations in reporting third-quarter results. Revenue grew 5% to $27.9 billion, while profits checked in at $0.56 a share. Both figures were slightly ahead of analyst projections.

Yet the beat isn't what matters here. Growth is what investors need to pay attention to, and Verizon has more of it than AT&T does. Wireless revenue improved 9% year over year, easily beating the 3% growth AT&T achieved during an otherwise good third quarter.

No one looking at subscriber data should be surprised by these figures. Verizon had 882,000 post-paid net additions during the quarter, more than double the 319,000 AT&T had during Q3.

Why the difference? Handset parity may have something to do with it. Apple (Nasdaq: AAPL) no longer sells exclusively to AT&T, and both carriers offer most Android handsets. Both networks also host significant numbers of Nokia (NYSE: NOK) and Research In Motion (Nasdaq: RIMM) handsets.

Therein lies the problem for AT&T. Now that users have the option to have any smart device on any network, they're signing with Verizon in ever-greater numbers.

My guess is marketing and word of mouth are responsible for fueling this trend. But LTE -- short for "Long Term Evolution," a high-speed wireless broadband standard -- may also play a role. Remember, it was an HTC Thunderbolt operating on Verizon 4G that blew away Sprint Nextel's (NYSE: S) best in tests conducted several months ago, leading some to favor the HTC device over the iPhone for a time.

Verizon has been aggressively rolling out 4G LTE service nationwide over the past year. AT&T won't go national with its LTE network until next year. Don't be surprised if Big Red's wireless business continues to grow faster in the meantime.

Do you agree? Disagree? Please let us know which telecom you think is the better buy right now using the comments box below. You can also keep tabs on the wireless industry by adding any of these stocks to your Foolish watchlist:

Fool contributor Tim Beyers is a member of the Motley Fool Rule Breakers stock-picking team. He owned shares of Apple at the time of publication. Check out Tim's portfolio holdings and Foolish writings, or connect with him on Google+ or Twitter, where he goes by @milehighfool. You can also get his insights delivered directly to your RSS reader.

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