NEW YORK (CNN/Money) - Cable companies and telephone companies are starting to look awfully similar these days...except for their stock performance.

Comcast and Cox Communications, the two big pure play cable firms, have lagged the four Baby Bells (Verizon, BellSouth, SBC and Qwest) over the past three months. Comcast (CMCSA: Research, Estimates) and Cox (COX: Research, Estimates) have been relatively flat while the Bells are up, on average, nearly 16 percent.

It appears that investors are starting to fret about increased competition from the Bells in video services, which is, of course, cable's bread-and-butter business.

Verizon (VZ: Research, Estimates) announced a deal last month with DirecTV to resell its satellite service. BellSouth (BLS: Research, Estimates) has a similar agreement with DirecTV while SBC (SBC: Research, Estimates) has a partnership with rival satellite TV service EchoStar.

And Qwest (Q: Research, Estimates) (which, I must admit, is kind of like the Ringo of the Bells...sorry to all you Richard Starkey fans out there...George has always been my favorite) has deals with both DirecTV and EchoStar.

Still, the two big cable companies have been better bets for investors over the past few years. Comcast and Cox are both trading at about where they were five years ago while the Bells have all plunged at least 35 percent.

This is the case because Comcast and Cox are the ones that have been successful in luring new customers to higher-margin product offerings. The two have been doing a very good job of beating the Bells in the high-speed Internet access game, for example, with cable modem services.

The Bells, in order to try and win back market share, all cut prices on their digital subscriber line (DSL) offerings last year. But Drake Johnstone, an analyst with Davenport & Co., thinks that these efforts have been largely unsuccessful and that the proof will come when fourth-quarter results come out Wednesday for Comcast and Thursday for Cox.

"When Comcast and Cox report, we'll see tremendous growth in high-speed and the market will wake up and realize that cable companies continue to lead," said Johnstone.

Of course, the Bells are hoping that video will be the final piece in the so-called "bundling" puzzle. If they can offer video in addition to DSL, local, long distance and wireless phone services, then customers might ditch cable in favor of the proverbial one-stop shopping experience.

But Henry Hewitt, manager of the Light Revolution fund, which owns Comcast and Cox, doesn't think that offering video will necessarily help the Bells win new customers. It just might stem defections a bit. And that's not anything to get too excited about.

"What's going on with the Bells and satellite guys is maybe a sense of desperation on the part of the Bells. DSL doesn't seem to be catching cable," said Hewitt.

In addition, the Bells probably need to worry about the emergence of technology that enables phone calls over the Internet, known as voice over Internet protocol (VoIP). This technology has been hyped for years but finally seems ready for prime time.

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And companies like Comcast and Cox, by virtue of their lead in the broadband access race, are positioned well to benefit from VoIP, said Greg Gorbatenko, an analyst with Marquis Investment Research, an independent firm focusing on telecom and cable.

The bottom line is that the Bells are facing erosion in their core business of local phone service while the two cable giants are continuing to add customers. Sure, the Bells should be able to offset some customer losses with their own VoIP services but the long-term growth prospects for the phone companies are still not that compelling.

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Analysts are projecting average annual earnings growth of about 13 percent for Comcast and 14 percent for Cox over the next few years while the Bells are all expected to post anemic earnings growth rates of about 2 percent to 3 percent.

With all that in mind, it looks like the cable guys shouldn't lag the Bells for much longer. "Comcast and Cox are the better plays," said Gorbatenko.

Analysts quoted in this story do not own the stocks mentioned and their firms have no investment banking ties to the companies.

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