A troubled new NHS 24 system for IT and call-handling will not be rolled out nationally until the end of 2017 - more than four years later than originally planned.
The Future Programme will now be phased in for some services from this summer with the aim of a national roll-out by the end of next year.
The system, more than £40 million over budget, was initially due to be ready for October 2013 but has run into a series of problems resulting in numerous delays.
Earlier this year, the planned June launch was pushed back to the “summer of 2016” after an issue that caused computer screens to appear blank.
It followed an incident in which the system crashed and staff had to resort to pen and paper to deal with patient calls.
NHS 24 said the new telephone system would be in place this year for services including Breathing Space, NHS Living Life, the musculoskeletal helpline, death certification, blood transfusion and Fit For Work.
It will then be introduced in one health board area to ensure it is working effectively before the national roll-out.
NHS 24 chief executive Angiolina Foster said: “We expect to have a functioning technology system tested and available later in the summer.
“However, we have recognised that ensuring our staff and operational environment are also fully ready to accept the technology is absolutely essential to making sure we can make a smooth transition to the new system.
“A recent review of our operations has identified that, while we continue to deliver safe and effective services every day, there are some key improvements required that will enable us to deliver even better, even safer services in future.
“We recognise that the past 18 months have been challenging for the organisation and know that the professionalism and dedication of our people has enabled us to give high-quality care to patients during this time.”
Health Secretary Shona Robison said: “While any delays to implementation are disappointing, patient safety must always come first. This is why NHS 24 has taken the decision to phase the roll-out of its Future Programme.
“This decision follows a comprehensive review of the new system which concluded that a phased roll-out later this summer, working towards full implementation across all health boards by the end of 2017, would be both safe for patients and deliverable by the organisation.
“The Scottish Government will continue to work closely with NHS 24 throughout this period.”