O2 Big Bundles are perfect if you use your phone a lot and want to get more for your money. There's no contract. Just top up £10 a month to keep your Big Bundle active.Here's what you get with a £10 Big Bundle sim.' 3GB data, unlimited minutes and texts. \r \n \r \n ' Up to 10% back on top-ups every 3 months with O2 Rewards, to spend on what you like. \r \n ' A whole range of offers, freebies, prize draws and privileges through the free Priority app - like a free drink at CaffÃ¨ Nero every week, and £5 main courses at Pizza Express. \r \n ' Data rollover, that lets you carry over your unused data from the previous month. \r \n ' Access to over 15,000 O2 Wifi hotspots up and down the country, so you can save your data for when you really need it.The O2 Big Bundle sim will work in any mobile handset, and the sim pack includes instructions on how to top up. As soon as you've topped up, we'll automatically swap your credit for your Big Bundle and your sim will be ready to use straight away.