Calling on international destination via your 0844 number
Calling on international destinations via your 0800 numbers is cheaper than you calling from your normal BT line.
This is because 0800 uk numbers providers do not use BT networks and gateways for international calling. The use internet protocols for international dialing which helps the cost to decrease making them charge way lower than BT.
Moreover, you can even route this number to anywhere in the world which means no mater you can go your customer can always stay in contact with you. However the calling rate will be different that that when you are dialing it locally.
Nevertheless, one thing is for sure that dialing on international destinations via 0844 number is cheap like anything.
This is another advantage of having an 0844 number on you than it being just a revenue generating number.