Hoax calls - where someone winds up a friend or colleague by pretending to be their boss or an important person - are almost as old as the telephone itself.
They have been a staple of TV and radio entertainment programmes since the 1950s when American comedians Steve Allen and Johnny Carson began making them on the Tonight show.
There are numerous examples of rich and powerful people being hoaxed. The Queen in 1995 spent 17 minutes talking to a man she thought was the prime minister of Canada. It was actually Pierre Brassard, a Canadian radio presenter and impressionist.
In 1998, Prime Minister Tony Blair took a call from a man claiming to be William Hague, leader of the Opposition. He immediately realised it was a hoax but took it in good humour. It was DJ Steve Penk's idea to try and get past the Downing Street switchboard and the caller was impressionist Jon Culshaw.
Foreign Secretary Margaret Beckett in 2006 thought she was taking a call from Chancellor Gordon Brown. It was actually impressionist Rory Bremner.
Cuban leader Fidel Castro unleashed a volley of abuse after being hoaxed in 2004 by a Miami radio station presenter pretending to be Venezuelan President Hugo Chavez.
Some of the prank calls made me laugh. Would love to have heard the one with the Queen