Most GPs stopped providing out-of-hours cover in 2004
Health experts have raised concern that Scotland's rural communities could be suffering when it comes to providing out-of-hours GP services.
NHS health boards now oversee the vast majority of services, after GPs were given the option to opt out in 2004.
The Centre for Rural Health and Centre for International Public Health Policy claimed alternatives were not always providing an adequate service.
The concerns were expressed to the Scottish Parliament's health committee.
It is holding an inquiry into out-of-hours healthcare provision in rural areas.
Traditional GPs were allowed to opt-out in a bid to tackle a recruitment crisis, brought about by doctors having to work excessively to provide 24-hour cover.
But David Heaney, of the Centre for Rural Health, said his impression was that "little progress" had been made on the issue of delivering out-of-hours services in rural areas over the past few years.
In a submission to the committee, he argued the focus should fall on emergency cases.
He added: "There is potential for more communities to contribute to improving the accessibility of service delivery through first responder schemes, but it is important that volunteers are used appropriately and supported in their role, and not seen as a replacement for services."
Echoing the concerns, Prof Allyson Pollock, director of the Centre for International Public Health Policy, said alternative providers, such as NHS 24, community pharmacists and ambulance personnel, were not a substitute for doctors providing traditional GP care.
She told the committee some health boards had also backed the use of volunteer "first responders" as an addition or substitute for GP services.
She added: "Only a relatively small proportion of medical emergencies fall into the categories of care which first responders can handle."
However as an example, one NHS authority, NHS Tayside, argued it provided comprehensive out-of-hours cover in Kinloch Rannoch, partly through the use of NHS 24 and doctor, nurse and ambulance services based in Pitlochry.
NHS boards also argue it costs more to deliver the services in rural areas, and, amid tighter budgets, a balance must be found between out-of-hours services and other health priorities.