The Tom Mabe one from Panicbutton is brilliant, but most of us are not that quick, so here are a few other methods:
1. Keep a police whistle or something similar handy by the phone and give them a blast or two;
2. Say, "This is Switchboard Monitoring. You have been identified calling this sex line during working hours. This call is being recorded and will be reported to your Manager. We have your extension number, please may I have your name."
3. Write yourself a short script as if you were an automated line and just keep reading it back to them. Even read something back from today's newpaper, but just keep going regardless of what they say. They soon think they have a wrong number.
4. Say "Greenstreet Taxis, how can I help you?"
5. Put on a really boring voice and say something like: " Its really kind of you to call, nobody ever rings me these days - I don't know why. My friend says its because I am really boring, But I don't think I am. Do you think I am boring? Because if you do, please say so - its really important you find these things out. You would tell me if I was boring you wouldn't you? I really like talking to somebody new, do you? What kind of things really bore you? I'm not boring you am I etc etc" Don't let them get a word in edgeways, they will soon get the message...
Finally 6> "I'm really glad you've rung, I have been tryng to get hold of somebody in your organisation for the past four weeks. When are you going to do something about my leak? I should warn you I am already on to Watchdog about you and Rogue Traders. You just keep fobbing me off with excuses - I'm staying on this line now I've got you until you fix it......... "