21CN will cost £10 billion (US$19 billion) through 2009, and is currently being trailled in Cardiff. The Welsh capital will be the first city to see full rollout, which will take place in three stages, BT said. In the first phase, from November 2006 to March 2007, 10 per cent of the 350,000 Cardiff-area voice customers will be switched onto the new network.

During the second phase, from April 2007 to May 2007, another 10 per cent will be switched over, and by the summer of 2007, all of Cardiff will be on the new network. Out of the total, 90,000 lines will support advanced services such as ISDN2 and ISDN30, BT said.

BT customers will get the upgrades without having to do anything, and will keep the same phone numbers. BT said it won't need to dig up the roads to carry out the work, with the changes mostly taking place at the telephone exchange.

There will be a gap of several months following the completion of the Cardiff rollout before BT begins switching the rest of its 30 million UK telephone lines onto 21CN in January 2008, during which BT said it will consult with other communications providers. The total switchover will involve upgrades to 5,500 telephone exchanges.

Leading the way

In 2004, BT was the first major telco to announce plans to move to an all-IP network. The new network is likely to give a further boost to the market for new services, including broadband, which has boomed in recent months. Ultimately the goal is to deliver converged, IP-based services, many of which haven't even been thought of yet, BT said.

The ongoing struggles of local loop unbundling (LLU) demonstrate, however, that BT's competitors will continue to face an uphill battle to offer services over BT's network – unless they pay wholesale fees, of course.

BT has been gradually opening up its exchanges to competitors for several years, and as of August 735,000 lines have been unbundled, according to a monthly report from telecoms adjudicator Peter Black of Ofcom. The unbundling efforts are coordinated through BT spinoff Openreach so competitors can offer services direct to customers.

Black had several criticisms of BT in the report, noting that migrations of single lines (as opposed to bulk migrations) were continuing to "deviate from planned quality levels," with "significant improvement" failing to materialise.

Bulk migrations were down due to unnamed "specific systems, process and infrastructure problems." This was partly due to heavier-than-expected demand, Black said. BT said it expects to improve on targets this month.