AT&T INC.'S planned $67 billion acquisition of BellSouth Corp. not only changes the U.S. telecommunications landscape but could cause an unexpected shift in the dynamic between Britain's Vodafone Group PLC and Verizon Communications Inc., the co-owners of Verizon Wireless.

Verizon has long been interested in buying out Vodafone's 45 percent stake in the venture, but has been holding out for the right terms. For months, Vodafone has been under pressure from investors to do a deal in order to generate cash for the company and pay out dividends to large shareholders. That gave Verizon the upper hand.

But now Verizon needs to get control of the venture more than ever, analysts say, just to keep pace with AT&T, which will take full control of cellular carrier Cingular Wireless and thus increase its exposure to the telecom industry's growth area. The power balance may have shifted in Vodafone's favor.

"In terms of negotiating leverage, I think there's been a slight shift toward more bargaining power for Vodafone," said Andy Belt, a telecom consultant at Adventis Corp., a Boston consulting firm.

The two sides may well find common ground.

Vodafone's stake in Verizon Wireless could be valued at as much as $45 billion, analysts say. Investors seemed to warm to the prospect Monday of a Verizon buyout, pushing Vodafone's shares in London 2.9 percent higher to 125 pence ($2.19). In 4 p.m. composite trading on the New York Stock Exchange, Vodafone's American depositary shares were at $21.90, up 90 cents, or 4.3 percent.

As the joint venture's name suggests, Verizon has always had greater brand and operational control of the company. That has led some Vodafone investors to ask recently why Vodafone Group's chief executive, Arun Sarin, doesn't bail out of the venture, especially because Verizon Wireless uses a different technology from Vodafone's other operations.

A sale of the Verizon Wireless stake could leave Vodafone, after returning some cash to investors, with enough left over to make acquisitions. One possibility: T-Mobile USA Inc., a unit of Deutsche Telekom AG. While Deutsche Telekom has said it aims to keep its U.S. division, the German company has considered selling in the recent past. T-Mobile USA also faces huge investments for new spectrum licenses in the near future. And it would give Vodafone its own brand name in the U.S. and a network based on the same technology it uses elsewhere.

But that isn't in the cards yet. "We would not be interested" in T-Mobile USA, a Vodafone spokesman said Monday. T-Mobile USA declined to comment.

Some observers say AT&T's bold strike means Verizon has to respond. Moving more aggressively to purchase all of Verizon Wireless is the most likely option, some say. Owning 100 percent of Verizon Wireless would help boost Verizon Communications' growth profile as it would be able to reflect all of the wireless carrier's growth.

It would also free Verizon Communications to offer wireless-related discounts and integrate its land line and wireless networks with new service offerings, particularly for business customers. As it stands, Verizon Communications must manage Verizon Wireless in the best interests of the joint venture.

Verizon Communications spokesman Peter Thonis said Verizon has a strong interest in buying out Vodafone, but added, "It isn't because we're reacting or responding in any way to AT&T."

Vodafone appears to be softening its stance on selling its stake. In a recent interview, Mr. Sarin said he wouldn't rule out a sale. "It's not a question of 'no, never, not at any price,' " he said. But, "we're not in a hurry," he added. "Verizon Wireless provides us a very good rate of return on our capital."

Because AT&T's integration of its land line and wireless business could have a negative competitive effect on Verizon Wireless, "the announcement of the deal may nudge Verizon (Communications) and Vodafone closer to each other," says David Barden, an analyst at Banc of America Securities. But, he adds, "It isn't clear it will nudge them enough to close the gap between them." Mr. Barden doesn't own shares in Verizon Communications or Vodafone. Banc of America has an investment-banking relationship with Verizon Communications, but not with Vodafone.

A sale would likely incur a hefty capital-gains tax for Vodafone. One way to mitigate that tax could involve Vodafone Omnitel NV, the Italian carrier in which Verizon Communications owns a 23.1 percent stake and Vodafone owns the rest. Verizon Communications could swap its holdings in Omnitel in part payment for Vodafone's Verizon Wireless stake.

Vodafone's Mr. Sarin has shown he is willing to quit countries when he thinks the time is right. The company said Friday that it was in talks to sell a majority stake of its Japanese business, which has struggled to stem a loss of customers. Some analysts say Vodafone's consideration of a sale in Japan could ease the pressure on the United Kingdom company to sell its stake in Verizon Wireless in the near term, but that shedding the U.S. business remains a possibility down the road.

"We view an exit in Japan as the better option than selling out of the U.S. at this stage," wrote Lehman Brothers in a research report Monday. But, "we believe that the willingness of Vodafone's management to take decisive corporate action could well lead to a U.S. exit over the mid- to long-term."