Over the last few years we noticed how are telephone costs had gone up line rental in particular; this is true whether it is BT or Virgin. So we looked for alternatives and found Vonage, for a one off fee for a box that plugs into out Internet router and a request to transfer the BT line to Vonage, we removed our whole reliance on the BT line. The telephone plugs into the box and hey presto our calls are now routed via the Internet to us.
The cost is only £6 a month with about an hours outgoing calls. As most of our calls are incoming it is quite a reduction in costs.