An update from the company Advanced on 11 August said it was still working to restore its systems following the ransomware attack on 4 August.
The statement said that the company had rebuilt is Adastra 111 system and it was 'currently working with the NHS England and the National Cyber Security Centre to complete the final steps on assurance before restoring service'.
It said services would be restored in a 'phased approach' and added that 'for NHS 111 and other Adastra customers, we anticipate the phased return to service to begin in the next few days.'
NHS 111 services use Advanced's Adastra system to access patient information, treatment pathways, refer patients to their GP and dispatch ambulances.
NHS England said that until the situation was resolved practices should continue to expect an increase in calls from patients. An update to practices said patients may be advised by NHS 111 to contact their practice directly.
It added: 'To support patients and 111, GP practices are asked if they could manage calls where possible and not direct patients to 111.'
NHS 111 is also unable to book patients directly into GP practices or access hubs until the systems come back online.
GP access hubs have been advised that NHS 111 will phone or email them with patient referrals, but warned that patients' NHS numbers will not be available for NHS 111 to include as part of the referral.
An update from NHS England said: 'There has been no immediate cyber security threat to NHS systems identified as a result of this ransomware attack. The attack was not targeted against the NHS, rather the third party software provider.
'While Advanced works to resolve their software problems, the NHS immediately put in robust defences to protect our own networks – this is in line with cyber security advice that has been widely circulated to data leads, digital teams and cyber security teams
'We are working closely with Advanced to restore services and only reconnect services when safe to do so.'
An NHS England spokesperson said: 'The public should continue to use NHS services as normal including NHS 111 for those who are unwell, although some people will face longer waits than usual, as ever if it is an emergency, please call 999.'
Advanced has said that it believes the ransomware attack it has experienced was 'financially motivated'. It said it was still investigating whether any sensitive data such as patient information had been accessed as part of the attack.