I got a phone call today from a 0800 number. What was strange was they hung up when I answered, being the paranoid that I am I suspected it was a scam. Sure enough a quick search of Google found the number and describes that it redirects to a 0845 number. A description of scam can be found here
The company involved is called “LBM 0800 scammers” which looks like IBM when in the URL (probably intended). I can’t believe that some businesses have a business model that involves tactics like this.
My advice is to never call back a number unless you check and verify that it is a number you recognise.