Hi Andy,
Try this. I phoned a friend of mine many moons ago, I can't remember why, and as I was dialing I came up with a wheeze. The conversation went like this.
Hi Steve, it's Lee.
Hi Lee, what can I do for you?
I've lost my little phone book with everyones numbers in. I've got a new one and I need your number to put in.
OK mate. Got a pen?
Yup, go ahead steve.
Steve then starts to read out his number. He pauses for a split second half way through, and I know he's twigged! He completes the number. Then the swearing and name calling starts!
Thats brilliant he sez. I'm gonna try that.
We hang up and some time later he phones back to tell me it worked on one of his sons and a neighbour. I have to admit, that was the only time I tried it.
People might be more intelligent now. We were quite thick back then.