We created a press ad that tested the proofreader's abilities to read every word on the page. The ad featured two very different numbers. If the potential proofreader called the first number they would automatically get through to the Job Centre's headquarters. Whereas if the proofreader called the second number, which can be found at the bottom of the page and is the one that looks like part of the terms and conditions copy, they'd get through to Big Communications.