The next step in this bitter battle could be a bidding war as other phone companies line up to help Mannesmann ward off Vodafone. "The offer isn't high enough," said Matthias Trimm, a fund manager at DWS Investment. "It will be a challenge for Vodafone to get a majority of shareholders to support this bid."
Mannesmann's first line of defence against a hostile takeover is a company by-law introduced in the 1970s that limits shareholders to 5 per cent of the voting rights regardless of their equity stakes.
Vodafone chief Chris Gent said on Tuesday that he expects Vodafone to overcome this hurdle because the rule is only valid until next June, and any transaction may take that long to close. German law also stipulates that a shareholder needs more than 75 per cent of voting rights to win management control.
Still, Mr Gent said he only needs 50.1 per cent of Mannesmann. That would allow Vodafone to change its supervisory board and, later, its management board.
The German company's acquisition of Orange, the UK's third-largest mobile phone company, from Hong Kong's Hutchison Whampoa, will make it Europe's top wireless company - a threat that sparked Vodafone's takeover approach.
The UK company said Mannesmann management will be offered senior positions in a combined company and that it sees no job cuts as a result of a takeover.
That still may not be enough to convince German unions to back the takeover. IG Metall, Germany's largest union, said thousands of workers at Mannesmann's mobile phone and engineering units in Dusseldorf will protest against the plan.