I think that Fay Mousse has answered your question. (I would trust any of the firms that offer this type of work).
However, if you're looking for work from home (with a reputable company) you might be interested in working as a route-checker for Deya. They've just won the contract to deliver all of the country's Yellow Pages and they also deliver Phone Books and Thomson's directories in many areas. Route-checkers phone customers to check that they've had their directory delivered. All calls are routed via Deya's own telephone system, so they don't appear on the checker's bill. (i.e. there's no 'up front' outlay with the job).
I've worked for Deya, delivering directories, and I'm now a Team Leader, so I know that they're a reputable company. I only found out about the route-checking opportunities when I attended a training session yesterday, so I can't give you an personal insight's into it, but you might want to check it out:
http://www.deya.co.uk/index.aspx?pageref=5130
Chris