Not sure if everyone knows about this, but if you have any of the following benefits:
Income Support
Income-based Jobseeker's Allowance
Employment Support Allowance (Income related) or
Pensions Credit (Guaranteed Credit)
You can get a BT phone line for £4.60 a month, which includes £4.50 worth of calls.
http://www.bt.com/includingyou/other...RL_calls_basic