BT customers who already have signed up to broadband and phone bundles will be upgraded to fibre broadband service, dubbed BT Infinity, for free.

BT Infinity provides customers with download speeds of up to 40Mbps and upload speeds of up to 10Mbps. The telecoms giant has plans to roll out the super fast service to about two thirds of UK households by 2015.

BT said that those customers who will sign up to one of its bundled services will be provided with an opportunity to upgrade to BT fibre services for free when they go live.

But, the firm remained tight-lipped about when it would make the fibre broadband service available.

At present, BT’s cheapest bundled package offering subscribers the chance to qualify for announced upgrade is More Broadband & Calls bundle. For the first three months the bundle is available for just £7.49, well below the standard £17.99 price. BT is offering line connection for free as compared with Sky’s and TalkTalk’s charges of £39 and £69.99, respectively.

However, subscribers will also have to pay £9.49 for line rental and £25 for an Infinity Activation Charge.

BT claims that it already has brought fibre connections to around 1.5 million households in the country. The figure is expected to soar to approximately 10 million by 2012, and 16.5 million by 2014.