Calling any 0800 number is free as a BT customer. In July 2015 OFCOM introduced changes making it free to call any 0800 number from any UK mobile. This means all BT customers may call an 0800 number without incurring charges, whether they are a mobile or landline customer. If you have an allowance of … Continue reading How much does it cost to call an 0800 number on BT?