Why am I charged for freephone numbers?
You may be charged to call certain numbers with the prefix 0800, 0870 and 0500 (numbers that are often free from landlines). This is always dependant on your network and your call plan; in order to clarify which numbers you'll be charged to call, you'll need to speak to your network directly.
However, most networks will allow you to call numbers beginning with 0808 80 for free. This is because these are helpline numbers for non-profit organisations, such as charities.