got this from another site--------
There is a new kind of mobile phone scam. A missed call will show on your mobile phone. The number is 0709 020 3840! The last four numbers may vary, but the first four numbers will remain the same! If you call this number back, you will be charged £50.00 per minute. People have complained about their phone bills, once they have realised the cost of the call, but apparently, this is completely legal. So beware, do not call back numbers beginning with 0709. We have spoken to the relevant departments during the course of the day, and found that this scam is actually true.

Please advise your users not to return any missed calls beginning with an 0709 prefix, as they will be liable for the cost of the call.

This is true lads, a couple of nurses here got had, one of my mates got hit for £500........watch out