Businesses are still in the dark over BT's 21st Century Network, according to new research from rival telecoms firm NTL.

Two in five of the telecom and IT managers interviewed for the survey were still unaware of 21CN, four years into the £10 billion (US$20 billion) project to replace BT's entire network infrastructure.

And 27 percent of the 200 managers interviewed by researchers 2Europe for NTL expected the project to be delivered late, after its 2011 deadline. Some 40 percent of network managers thought BT would be one to five years late switching customers over to the new network.

According to 86 percent of network and telecom managers, bandwidth improvements would be the top benefit from a next generation network. Voice, data and video availability on mobile devices was another benefit, highlighted by 67 percent, and sharing contacts across different phones and mobile devices was a benefit foreseen by 63 percent.

NTL took the opportunity to boast that it had "already completed" the setup of its next generation network. Stephen Beynon, managing director at NTL, called 21CN "a massive project akin to the engineering feat of digging the channel tunnel".

He added: "BT has committed to creating a next generation UK-wide network by 2011 but is being coy with the details".

BT did not provide immediate comment in response to the survey. Today, the company announced that retail boss Ian Livingston would replace Ben Verwaayen as chief executive on 1 June.

In spite of the boasts, NTL has not been without its own network problems. In September, north London customers of Virgin Media - created by the merger of NTL and Telewest - were left for 30 hours without broadband services. Virgin said it had been "undertaking a major programme to improve the reliability and on-going maintenance of our vast network."