O2 are one of the UK’s biggest mobile network and to celebrate this they are giving away free o2 calling cards. You can get £1 credit just for liking their facebook page, you can also get another £5 credit by telling them which is your favourite national treasure and why. For example mine would be the 2012 London Olympics as it will be one of the biggest events the UK has held in its history. So to get your free o2 calling card credit click the text below. Oh and by the way this is not confirmed but you might also be able to use the calling credit around the world. So happy calling guys!