Which 118 has got your number?

But the Communications Workers Union said that fierce competition in this sector would mean that some jobs would only be temporary.

The Number, which is based at Cardiff Gate, is one of several companies hoping to dominate the directory enquiries market when BT's 192 service is switched off this weekend.

Instead, subscribers will have to dial a six-digit number beginning with 118.

The US-owned company, which has launched the 118 118 service, said 700 permanent posts will be filled in Cardiff and Plymouth over the next week.

The firm will have then created 2,000 jobs since last September at an average rate of 150 posts a month.

For months several companies have set up call centres hoping to take business off BT.

The Number already employs 700 at its Cardiff call centre and Friday's announcement boosts that to 1250.

Another firm, Conduit, employs a similar number at two call centres, one in Cardiff and another in Swansea.

Fierce competition

The 118 services are now a major employer in Wales, but union leaders are already warning that fierce competition may lead to job cuts over time.

The Communication Workers Union (CWU) said it feared many of the new jobs would only be temporary, claiming that some workers were on minimum wage rates despite working long hours in stressful conditions.

The Number will be one of at least 15 companies offering directory enquiry services when the old 192 is switched off at one minute past midnight on Sunday morning.

"We are extremely pleased to announce this further wave of British jobs to meet the growing demand for 118 118," said chief executive Chris Moss.

Analysts say the new market will create 3,500 new jobs

"The welcome, skills and commitment we have found in Cardiff and Plymouth has been a tremendous boost - there is no reason why the UK cannot be the best in the world."

The CWU does not have recognition rights at many of the new companies but fears that pay rates could be lower that the industry average.

BT pays about �15,000 to its directory enquiry staff, but that figure is at the higher end of the scale. Pay rates of �11,500 or lower are more typical.

The CWU is fighting plans by BT to transfer directory enquiry work to two new call centres in India and it suspects some of the new entrants will have centres in overseas countries, including Malaysia and Hong Kong.

Staff working in the UK and Ireland will be working from call centres in areas including Dublin, Dumfries, Birmingham, Glasgow, and South Wales.

Some industry analysts have estimated that opening up the market will create 3,500 new jobs, but few expect all the new entrants to remain in the business indefinitely.