O2’s International Calling Card costs £5, and offers low rates to a number of countries around the world. You simply dial a number (free from O2 mobiles), enter your unique PIN then dial the number you want. Easy.
The card encompasses dozens of countries, from Afghanistan to Zimbabwe. The rates are as a low as 1p/min (for Indian landlines and mobiles). All calls to the USA are 2p/min. Check out the full list of rates here.
You don’t have to be an O2 customer to use the International Calling Card. The number is compatible with all networks.
(Thanks to mrbg07546 at HUKD)