Data communications provider Entanet is the latest company to sign up to BT's trial of 40Mb fibre-to-the-cabinet broadband services.
The tests in Muswell Hill, London and Whitchurch, Cardiff, will utilise existing end user broadband infrastructure alongside BT's 21st Century Network for a period of six months.
While BT Wholesale is currently aiming for a downstream of 40Mb and an upstream of 2Mb, Entanet claims the latter could be increased to 5Mb.
Head of marketing at the firm Darren Farnden said that the speed was achieved by connecting street-located cabinets to telephone exchanges using fibre links and high bit-rate DSL technology.
Mr Farnden added: "What this means is that the customer's experience should improve for applications such as video telephony, high-quality voice, web browsing and video streaming."
Earlier this week, broadband wholesaler Griffin revealed that it would also be taking part in the tests, which begin on July 1st.