Do you regularly dial outside the UK? How much does your telecom company charge you for international calls? Many companies now offer phone or calling cards which offer extremely good rates. Alternatively, you could open a prepaid calling account which can also be used to call from abroad!

From personal experience, we have also found that telesavers.co.uk provide a cheap, reliable service and have many destinations (such as Thailand and China, for only 1p per minute!).