Cable firm NTL is taking control of Virgin Net, the UK's fifth largest internet service provider, the latest in a series of similar deals.
Ntl and Virgin Media Group launched Virgin Net in 1996
NTL's UK arm is acquiring the 51% stake in Virgin Net that it does not already own for an undisclosed sum.
Launched in 1996 as a joint venture between NTL and the Virgin Media Group, NTL is buying out its partner as well as shares owned by current management.
NTL said Virgin Net would continue to trade under its existing brand name.
Virgin Net has about 590,000 subscribers.
"The is a very good acquisition for NTL," said its UK chief executive Simon Duffy.
The transaction is the latest in a flurry of deals in the ISP sector which has been consolidating rapidly over the past two years.
Claranet, one of the UK's few remaining independent ISPs, recently agreed to buy the UK arm of Nasdaq-listed firm Via.Net Works for £7.3m.