Dial a doctor: 2,500 Dr Who fans try to ring Time Lord's mobile

But it was another set of figures that got some fans really worked up  -  the Time Lord's phone number.

The digits had been flashed up on screen several times in the previous week's episode as the Doctor's sidekicks Sarah Jane Smith, Martha Jones and the Torchwood team contacted him.

The Doctor's private mobile number appeared on screen during the final episode

More than 2,500 fans  -  whipped into a frenzy of anticipation after a cliffhanger ending in which it appeared that star David Tennant might be leaving as the Doctor began regenerating  -  dialled it before the last episode aired on Saturday.

One fan complained: 'They showed that number so many times, as if they were asking for it to be called.'

But their attempts to contact their hero on his personal number - 07700 900461 - came to nothing when they discovered that it would not connect.

Writing on the BBC's website, one disgruntled viewer said: 'Grrr  -  I phoned the Doctor's phone number but there was just an annoying network message.

'What's the point in showing a phone number if you're not gonna use it?!'

Ofcom, the TV industry watchdog, said the number was simply one reserved for use in television dramas.

A spokesman added: 'It wouldn't have cost anything to call these numbers because they are not real.

'If someone did call it they would hear either a dead dial tone or number unavailable. There are a series of phone numbers we assign to producers for TV series.'

A BBC spokesman said: 'BBC complied with Ofcom who supplied the programme with a safe number that was inactive and reserved specifically for the use of TV programmes.'

Saturday's finale was watched by 9.8million viewers at its peak, taking 47 per cent of the total audience share.

But the show experienced a backlash from some viewers who felt tricked by the Doctor's non-regeneration. Instead, Tennant's character quickly recovered to defeat the Daleks and their creator Davros.

Tennant will return in a Christmas episode this year and four specials next year, but he is not yet confirmed for the next full series in 2010.

Later this year he will play Hamlet for the Royal Shakespeare Company.

Bookmaker William Hill has tipped the three favourites to succeed Tennant to become the 11th Doctor as David Morrissey (who will guest star in this year's Christmas special), Robert Carlyle and James McAvoy.