The service was created by the Law School of the University of Wales, in Cardiff, following research by postgraduate students that began more than two years ago. Most callers seek advice about the workings of the much-criticised 1994 Criminal Justice Act.
In the early 1980s few travellers, whether on the move or living on authorised sites, had access to a telephone other than the nearest kiosk. Yesterday one of the researchers, Sue Campbell, said that almost 50 per cent of travellers now have access to mobile telephones.
The latest count of Britain's itinerant population shows that 9,000 of the country's 13,500 caravans are on pitches run by local councils, the remainder being illegally parked in lay-bys or on private property.
Professor Phil Thomas, the project director and an authority on civil liberties law, said of the service: "It puts travellers in touch with solicitors willing to act in cases such as evictions, site conditions and planning appeals."
Where necessary test cases would be brought and judicial reviews in the High Court sought, he said.