Yes, but the various networks have their own international call charges and there's no comeback to your network when there's a hitch with a calling card.  I work for a network (I'm not saying which one) and got a customer calling the other day to say we'd charged her for a call overseas which she used a calling card for.  I checked her call history and she hadn't been charged for ANY overseas calls BUT there was a charge to the 07744 number that the calling card gives as their service number to get the whole thing set up.  We charged her at the per minute cross-network charge just to ring that number to get it set up - she was on the line for quite a few minutes and that particular call cost her nearly £3. (with most networks, an 11 digit number beginning with 077 is classed as a mobile number, and moreover as a cross-network mobile number!) .  Calling cards are great if you know what you're doing but if you make an error, it's between you and the company issuing the calling card.  As it's always easier to get in touch with your network, the network are the ones that get all the 'flak'.  Nowhere in the Terms & Conditions of ANY mobile network does it say "our International call charges are £xyz per minute but you'll probably get it cheaper if you use a calling card".  Any problems incurred through involving 3rd parties and you're on your own.  By the way, the customer who called to complain was calling an overseas country which was very cheap indeed on our network's own tariff - and she didn't even know this!