The calls are not free any way they come out of your inclusive cross network minutes,which you pay a rental for. So if say you have 200 minutes and they cost you £25 a month.The calls are in fact costing you 12.5p a minute.
and
Thats a good call I guess! But if you have x-net mins, its much better than paying 10p a minute!!
I think using the landline to call 0870, especially at evenings, and weekends is cheaper, or even better using 18185 during the day.
However a contract mobile, which would have to be on O2, or orange to use the 07744 code might charge a normal £20-£30, however by getting a non top of the range mobile, and opting for cashback, and getting a new contract 12 months later, and selling the old phone, does bring down that monthly cost, and therefore the cheapest way to call 0870 would be via the mobile with O2, and via 07744 with Orange.
And don't forget the free texts as well by using the mobile!!
And also don't forget to cancel after 12 months. Staying on a contract at £30 per month is not as good as cancelling the contract and taking a new one out with 6-10 months free line rental, and a new phone, and enabling you to sell the old one in the local paper for about £20.