Telecoms firm believes BT customers could save £448 million by switching provider.
Phone company TalkTalk is now providing free local landline calls for its customers at any time of the day.
The company claims that 11.8 million BT customers would be able to save a total of £448 million if they switched to TalkTalk. This is based on analysis by the company, which showed that voice-only customers would save £45 a year compared to BT, while home phone and broadband package subscribers would save £38 annually.
Wendy Becker, managing director of TalkTalk, said: "We are committed to providing our customers with the best value package on the market - whether that be for their home phone or their broadband." Ms Becker added that she believes the deal is "unbeatable", given that seven out of ten UK calls made by TalkTalk customers are local.
Landline companies have suffered a dip in revenues over the past few years as first mobile phones and then voice over IP (VoIP) services began to eat into their customer base. VoIP companies - such as Skype - allow users to make phone calls over the internet, meaning free calls can be made to anywhere in the world.
According to figures from analysis firm Telegeography, there were 25.3 million consumer VoIP lines in western Europe at the end of 2007.
