BT is taking unprecedented action by challenging Oftel in court over a ruling made in March.

BT has asked the High Court to let it appeal against Oftel's ruling, which said that BT must pay half the cost of auto-diallers - boxes that plug into customers' phone sockets and automatically route calls to other networks - according to a Reuters report,.

The ruling came after BT failed to comply with a European demand that dominant carriers must provide automatic facilities for routing calls to competitors by the start of this year. BT now has until the end of this year to comply with Oftel's demands.

This is the first time BT has taken legal action against Oftel, the government's telecommunications watchdog.