People can now dial 111 rather than the previous 11-digit number to receive medical advice.
In the past, callers paid the price of a local call from a landline but mobile users often faced much higher charges.
The change brings Scotland into line with England, which has been using the 111 number since February.
The  NHS 24 service will remain exactly the same, with nurses and other healthcare professionals available to give advice on non-urgent health issues 24 hours a day.
The introduction of a freephone number was first announced in January last year by Scottish Health Secretary Alex Neil, who said it would remove a barrier to healthcare services.
It was welcomed by poverty campaigners including Caroline Mockford who was charged almost Â£8 by her mobile provider for a call to the helpline.
She later submitted a petition to the Scottish Parliament, calling for the phone charges to be scrapped.
A new freephone number has been introduced for the NHS 24 non-emergency helpline in Scotland.