Phone giant Verizon (VZ) - Get Report is starting to feel a little squeezed on all sides.

Shares of the No. 1 telco have been on a slide this year, thanks to its much-debated merger deal with

MCI

(MCIP)

and the subsequent bidding war against

Qwest

(Q)

. But a rash of additional concerns about the rate of decline of Verizon's core business and a potential slowdown in its wireless venture have helped push the stock to a 52-week low this week.

Competition seems to have come calling at the New York telecom titan's door.

On the home front, the long anticipated cable threat is starting to materialize. Outfits such as Time Warner Cable and

Cablevision

(CVC)

, which have large operations in Verizon's eastern-state turf, are starting to see meaningful growth in phone service subscribers. Both companies have been signing up 1,000 to 2,000 new customers a day for voice-over-the-Net calling services. This trend is disturbing, not only because it promises to speed up the 4% annual shrinkage rate for Verizon's local phone line count but because it tends to siphon off some of the higher-spending customers first.

Until now, Verizon has been able compensate for losses in its old-line business with heady gains by its cell-phone service,

Verizon Wireless

, a joint venture with

Vodafone

(VOD) - Get Report

.

But observers say reports Wednesday of stronger-than-expected first-quarter subscriber growth and lower defection rates from No. 1 and No. 3 wireless telcos

Cingular

and

Sprint

(FON)

may spell bad news for Verizon Wireless.

While there's a chance that Verizon Wireless may report its own strong subscriber numbers next week, some investors and analysts say the odds are getting longer.

"They all can't be great," says one Wall Street wireless analyst who asked not to be identified.

Falling
Verizon's 2005 slide

Verizon Wireless added a record 1.4 million net new cell-phone customers in the fourth quarter, benefiting from a strong holiday season for wireless sales and unhappy AT&T Wireless customers switching service. But Cingular, the venture of

SBC

(SBC)

and

BellSouth

(BLS)

that bought out AT&T Wireless last year, says it cut its monthly churn rate to 2.2% from 2.4% in the previous quarter, while adding 1.4 million net new users of its own.

The stars aren't exactly aligned for Verizon Wireless at this time, say observers. Analysts' consensus calls for the company to post a net add number of 1.34 million. But Wednesday's updates from Cingular and Sprint suggest that the wireless winds have shifted and are not entirely at Verizon's back.

That's not to say the big phone shop is short on plans for a counteroffensive.

Verizon Wireless is speeding up its plan to offer nationwide fast wireless Net access with a network upgrade called evolution data only, or EV-DO. As

TheStreet.com

has reported, people close to the EV-DO plan say Verizon will hit by midyear its 150-city year-end target. The company is racing to be the first of its peers to offer high-speed service and win more laptop-toting business customers.

And perhaps an even more telling sign that Verizon is feeling the competitive pinch is that the company has introduced two offerings aimed at cable rivals that also run the risk of undercutting its own business.

Earlier this week, Verizon said it would offer stand-alone digital subscriber line, or DSL, service -- an offering that was historically part of all-important communications bundle. The move would allow non-Verizon customers to take the DSL service and, perhaps unintentionally, it would allow Verizon customers to drop the phone service and take just the Internet access.

Similarly, earlier this month Verizon launched its voice-over-Internet protocol, or VoIP, calling service to battle the cheaper offers from the cable companies as well as upstarts like

Vonage

and

Skype

as well as Internet giants

AOL

and potentially

Google

(GOOG) - Get Report

. The approach shows Verizon is willing to go outside its territory as competition heats up. But it also threatens to cannibalize Verizon's own conventional phone business.

Verizon shares were down 11 cents to $34.05 in midday trading Wednesday. Verizon is expected to release its fourth quarter report next Wednesday before the market opens.