However, telephone conversations are not so simple. You cannot just excuse yourself and go to the loo when there is an oddball on the other end of the line, especially when you think he is the Canadian premier. Such situations call for the discreet charm of the monarchy.
The 17-minute conversation that the Queen held over the airwaves with Pierre Brassard, a Canadian disc jockey masquerading as the PM, offered a rare insight into those skills. With that high-pitched voice familiar to those pausing between courses at Christmas lunch and to generations of corgis, the Queen gave a flawless performance. She may have muffed a few lines, with her curious brand of transatlantic franglais, but at least she tried to speak the lingo. And, surrounded by officials, she could not, even if she did suspect a hoax, say to her caller: "Come off it, laddie, if you're the Prime Minister, then I'm Valerie Singleton."
Instead, the Queen diplomatically let her caller do the talking, not even calling a halt when asked whether she would be wearing a costume for Hallowe'en. (Her Majesty will not, she said, be giving the broomstick and black hat an outing down the corridors of Buckingham Palace.)
And when it came to politics, she played her hand cautiously, agreeing in principle to a request that she should make an appeal for Canadian unity before today's referendum on whether Quebec should break away from Canada. All of which goes no further than the monarch's rights, as defined by Walter Bagehot: "the right to be consulted, the right to encourage, the right to warn".
Perhaps the most surprising and reassuring aspect of the whole bizarre episode is to discover a figure who seems to say in private much the same as she says in public. So it is a pity that most British broadcasters censored the hoax call and refused to let listeners and viewers hear the Queen actually speaking. No doubt the BBC, for example, has scruples about broadcasting the result of deception. But perhaps it is also prey to Bagehot's fear that to let daylight in on the monarchy is to destroy its magic.
On this occasion, the senior member of the Royal Family gave a good account of herself and no harm would have been done. And hearing mum on the wireless would have been good for her children. It might even have helped her son and heir with his own less discreet telephone technique.