If you're a social butterfly, you can run up quite the bill on your mobile phone. Don't worry; we're here to help with a list of apps for your iPhone or Android phone that offer free calling and texting services.
Do bear in mind that these services all use either Wi-Fi or 3G, and data charges may still apply; but if you don't see a significant reduction on your bill, we'll eat our hats.*
*Hat-eating not guaranteed.