Communications watchdog Ofcom has published a useful list of what UK numbers mean and how much each will cost to ring.
The sheer number of options for UK consumers makes it difficult to keep track of what costs national rate, local rate or premium rate.
"If you're confused by call charges or don't know your 03 from your 0845 numbers, then we have the perfect guide for you," say Ofcom.
"There are so many different types of phone number these days that it can be hard keeping tabs on how much they cost to call."
"Our guide looks at some of the common numbers in use today, what they are used for and how much it costs to call them from a BT landline," Ofcom continues
"You can then download the guide, print it off and keep it by your phone so that you've always got the facts at your fingertips."
You can check out the guide at http://www.ofcom.org.uk/files/2009/08/numbering.pdf but be aware that it's a PDF file.
Alternatively you can call 0845...