The number to dial is 0131 556 8400. That reaches the Scottish Executive, where Alex Salmond, the Scottish First Minister, awaits a call.
Diplomatic protocol requires that the PM offer his congratulations on the election of other government leaders. Tony Blair did so for Nicolas Sarkozy in the passable French that he learned at Fettes College. Just across Scotland's capital from his alma mater, the phone isn't ringing. This isn't protocol, but the politics of the playground. Although Blair met Colonel Gaddafi and brokered peace between Ian Paisley and Martin McGuinness, the Scottish Nationalists are supposed to be content with a call from Douglas Alexander.
Perhaps the Westminster leadership limbo leaves it unclear who has to do the dirty work of dealing with a Nationalist leader whom the PM and his successor loathe. Perhaps they think that if they ignore him, he might go away. But the best guess at the reason for Labour's behaviour is that the party is in denial.
Labour had a better result than most feared, down by only four seats. Yet warning Scots that a vote for the SNP would have consequences akin to biblical famine and pestilence did not stop the Nationalists gaining 20 seats, ending on a knife edge of 47 to Labour's 46. With the Tories and Lib Dems abstaining, a couple of Green votes were enough to ensure that Labour's Jack McConnell was tipped out of office, handing the Nats power for the first time in their 73-year history.
The evidence of denial was led by Philip Gould, who last month offered NS readers his curious reading of the campaign as "Labour at its best". He came north to repeat this to MSPs, telling them how proud they should be. From Westminster, it may seem that the loss of power on the Celtic fringe, with Welsh Labour holding on to office with little power in Cardiff, is an unfortunate consequence of midterm blues: from Holyrood, it is a calamity. Ten years ago, Labour won 56 out of 72 Scottish seats at Westminster. At Holyrood, 37 Labour constituency MSPs remain and many more have turned marginal. Under a new voting system, the party lost a third of its councillors and now has majority control of just two councils.
Now, disbelievingly, Labour faces four years in opposition and has some hard questions to answer. Why did Scots think they were being taken for granted? What has the party delivered for the bleak town centres it represents, from Brown's Kirkcaldy to McConnell's Wishaw? How did it lose its role as the political vehicle for change, aspiration and Scottish identity?
Midterm blues can take some of the blame for the loss of power. Brown can blame McConnell. McConnell can blame Brown. Both can blame Blair. Or they could take comfort from how Labour's vote did not collapse and the SNP victory margin was eye-wateringly tight.
Labour's biggest danger is that it will believe its own spin and ignore the need to renew itself and its hollowed-out organisation, or to purge the numpties - the dead wood, underperformers and time-servers who control tiny local party machines - from the ranks of its MSPs and MPs.
The lack of a call from No 10 doesn't look good for Salmond, either. Looking miffed as he waits by the phone, he seems less like a wannabe statesman than a lovestruck teenager. But, for all that he is 18 seats short of a working Holyrood majority, he has set quite a pace for his new administration.
Much of this was set out in mid-March, when a 49-item, "first 100 days" strategy was published, ranging across big-budget commitments for freezing council tax, more police, nurses and teachers and free prescriptions; a start to legislation on waiting-time guarantees; writing off and replacing student debt; and direct elections for health boards. This was coupled with easy bits, from appointing a council of economic advisers to declaring a two-month winter festival from St Andrew's Day to Burns Night. So far there has been a slimmed-down ministerial team, a block on new nuclear power, publication of a long-suppressed report into government spending, a call for Scotland to have its own Olympic team and abolition of Forth Bridge tolls.
Being a canny sort, Salmond is positioning each proposal to make it hard for his opponents to vote against. He is also holding back on the tricky parts. He has not yet set about introducing a local income tax or replacing public-private partnerships with an arm's-length agency issuing bonds. And he has yet to admit to his own party that the Holyrood arithmetic means they won't get their independence referendum any time soon.
He has signalled the fights he wants to pick with Downing Street, including a claim on some welfare budgets and a share of North Sea oil revenue. That is where the Salmondista revolution is being watched with most interest, but it may prove hard to press for more powers or cash if Downing Street won't even speak to him.
Douglas Fraser is Scottish political editor of the Herald