The 0870 telephone number is used by companies as a nongeographic landline number. Companies prefer this to avoid any regional bias from customers and colleagues. However, while you can call some 0870 numbers free from land lines in the UK, you are charged a premium rate if you call from a mobile phone. It is possible to use a web service to find alternative landline numbers for the 0870 number you are trying to reach.
Go to the Say No to 0870 website (see Resources).
Click on the "Search to find an alternative number" link in the toolbar at the top of the page.
Enter in the appropriate field either the 0870 number or the company name you want an alternative number for.
Click on the "Search" button next to that field. A new window will pop up displaying the numbers available for that company, including the free phone numbers and landline numbers.