BT has given its new super fast broadband service a snazzy new name, "Infinity", as it's announced it is to launch in the UK from 25 January.

Using fibre optic tech to offer download speeds of up to 40Mbps, the service will cost from £19.99 per month. Upstream speeds, at up to 10Mbps, will be the fastest in the UK, says BT, but will only be available to those signing up to a £24.99 a month package - £19.99-ers will get upload speeds up to 2Mbps.

BT is claiming Infinity-powered downloads will be up to seven times faster on iTunes, while online gaming will be up to 30% faster.

New and existing BT Total Broadband customers in an enabled exchange area can opt to pay out for the service by signing up to new 18-month contracts which will see a £50 connection charge for those on the £19.99 monthly charge. There's also BT's line rental of £11.54 per month to pay too.

The £19.99 contract allows a monthly usage of 20GB, while the £24.99 is called "unlimited" but subject to BT's fair usage policy, more of which, and other small print, as well as details on coverage areas, can be found on BT's site.

UPDATE/COMMENT: After some brief calculation, we worked out that going full pelt on the £20 service for just 67 minutes would take you over the 20GB cap. Of course as many commenters have pointed out below, the chances of you hitting 40Mbps speeds at all are rather slim, but at even half that, a couple of hours of intense YouTube video watching would take you over the limit.

If you have anything other than the lightest web usage, we'd suggest plumping for the more expensive option -  there's nothing "Infinite" about the the £20 Infinity package.