The 0.5p calls are to a landline and you do not need a calling card, you dial 0844 200 8585 and then you are talked through the system wich is very easy, you just continue with 0066 and then the number and hash and hey presto.
To call a mobile it's 1p a minute and the access number is 0844 861 2121.
I found this through the money expert website and is a good source of money saving tips. I have attached a link and hope it can remain as it is an independant search engine.
http://callchecker.moneysavingexpert.co ... llchecker/
