Vodafone has told some institutional investors that it will seek shareholder approval to purchase AT&T Wireless at an extraordinary meeting, regardless of whether it is required to do so under UK listing rules.
Mr Arun Sarin, chief executive of Vodafone, has recommended to his board that Vodafone should launch a $30 billion-plus (€23.4 billion) bid.
A board meeting to approve the deal is understood to have been held yesterday afternoon.
The move to seek investor approval is likely to allay fears among some large shareholders that the mobile operator could seek to pursue a deal that was highly dilutive to earnings.
Some analysts have suggested that, depending on how much Vodafone pays for AT&T Wireless, a deal could dilute earnings by more than 10 per cent.
Vodafone would need the support of at least 50 per cent of its shareholders to pursue an acquisition of AT&T Wireless.
With the deadline for bids for AT&T Wireless closing at 5 p.m. New York time today, Vodafone is expected to submit a formal bid.
It will join Cingular, the second-largest US wireless operator, which confirmed yesterday it would submit an all-cash offer for the group.
Nextel, another US mobile operator, is also understood to be considering making a bid using its highly valued shares.
The board of Japan's NTT DoCoMo will also decide today whether to bid, although it is expected not to join the fray given concerns of NTT, Japan's leading telecoms group and the majority shareholder in DoCoMo.
AT&T Wireless has told bidders that it will reach a formal decision by February 29th at the latest.
Vodafone, which owns a 45 per cent stake in Verizon Wireless, the leading US wireless operator, has been in talks to sell its holding so that it can mount a bid for AT&T.
Under US regulations, Vodafone must divest its Verizon stake if it gains control of another wireless operator.
Some Vodafone shareholders expressed reservations about the likely dilution to earnings of a Vodafone bid.
But there were also signs that some investors might support a deal.
"I trust the Vodafone management," said Stuart Fowler, head of UK equities at Axa, a top-10 shareholder in Vodafone.
"When you look back at all the telecoms operators over the last five years, they are about the only company that has not put its financial strength at risk."
However, Ms Karen Robertson, investment director at Standard Life, said: "If the numbers being bandied around on earnings dilution are right, we have concerns about what impact a deal would have financial returns going forward."
Vodafone will next week launch a commercial third-generation (3G) service for laptop computers across seven European countries, the group said.
