ORANGE last night became the first mobile phone operator to move into the landline market in the UK with the introduction of a fixed line service for businesses.

The firm will operate the service from its business customer contact centre in Darlington.

But the company said last night there were "no plans at present" to increase staff.

However, if the service proves to be successful, jobs could be created further down the line.

Orange said it will undercut BT charges by up to 20 per cent with Orange Landline for Business, which will provide a fixed line service to existing and new Orange mobile business customers.

Businesses will be able to replace their landline rental and call services with a single Orange package catering for mobile, national and international needs, the firm said.

Orange is able to provide the service following Ofcom's Wholesale Line Rental programme, under which BT is obliged to allow operators to offer both line rental and calls to customers over its network.

The service will include discounted rates for calls between Orange landlines and Orange mobile numbers, as well as for calls to customers' top ten Business Circle landline numbers.

Orange is owned by France Telecom and employs 12,000 people in the UK.

Last week, the state-owned company said revenues for Orange in the UK were up 0.8 per cent to 5.8bn euros (£4bn) in 2005 after its customer base grew 4.5 per cent to 14.9 million by New Year's Eve.