Use 07744 numbers for free international calls, you can dial 07744 from your Orange, Virgin & T-Mobile to call international destinations using your FREE cross network minutes. O2 users can dial 0870 alternatively. Please dial 0844, 0871, 0911 from BT Landlines. Chat about it in - 07744 Discussion Forum

27 Apr 07 - O2 Update (new customers) - 0844, 0845, 0870 will be 20p flat for new customers

This news only apply to people who bought or upgraded their contract on or after 27th April 2007.

We are very sorry to bring another sad news for O2 users of 0844, 0870, 0845 numbers that the network will no longer consider calls to these numbers as part of inclusive minutes from 27th April 2007.

All calls to 0844, 0870, 0845 on O2 Mobile will be charged at 20p per minute flat rate. This change will only affect new and upgrade customers as of 27th April 2007.

We suggest all users who have O2 contracts and use these to call 0844, 0845 and 0870 to not upgrade the contract. Upgrading the contract will mean that these calls will no longer be included in inclusive minutes.

Details about this news can be found here
http://www.o2.co.uk/mobilestariffs/tariffs/specialnumbers