Faster broadband should be available at half of Cornwall's telephone exchanges by autumn 2012.
Liskeard, Callington, Gunnislake and Launceston are being upgraded soon.
It is the latest phase in a £132m project to roll out so-called "superfast" broadband to 90% of homes in Cornwall and the Isles of Scilly.
Funding is coming from the Superfast Cornwall partnership between BT, the European Union, Cornwall Council and Cornwall Development Company.
Eight Cornish exchanges have already been upgraded at Chacewater/Chiverton Cross, St Agnes, St Day, Portreath, Devoran, Leedstown, Stenalees and Par.
BT predicts downloads speeds using fibre optic cables of up to 100 Mbps (megabits per second) by 2012.
The project, due for completion in 2014, could provide a blueprint for future rural broadband projects.
Director Karen Patterson said: "It is a massive leap forward.
"To take just one example, we are now using superfast broadband to distribute the latest movies to our hotel customers around the UK faster than ever before.
"The technology and expertise we have available allows us to operate on a national scale here in Cornwall and compete successfully with very big companies."