More than nine million patients receive out-of-hours care in England every year but concerns have been voiced about the quality of treatment.
Before 2004, GPs covered the needs of their patients during non-office hours, at weekends and bank holidays.
A contract negotiated between the British Medical Association (BMA) and the Government in 2004 allowed doctors to opt out of providing this care.
In return for giving up £6,000 a year in salary, they could hand over responsibility for patients from 6.30pm to 8am on weekdays, and on all weekends and public holidays.
Nine out of 10 GPs chose to do so, with primary care trusts (PCTs) taking on the role of providing cover.
They now commission out-of-hours services from a range of organisations including private firms, GP co-operatives and in-house teams at the PCT.
Earlier this year, the Royal College of GPs called for a review of the use of overseas doctors in out-of-hours care.
Last year, the NHS Alliance group of NHS staff said family doctors should take back responsibility for providing out-of-hours care as patients had lost confidence in the new arrangements.
In March 2007, the Commons Public Accounts Committee (PAC) condemned the Government's preparations for the handover from GPs to PCTs as "shambolic".
The PAC report put the cost of the new out-of-hours service at £70 million a year higher than predicted. It said the Department of Health "failed to explain" whether the service should cover just urgent cases or any request for help around the clock.
