The new non-emergency NHS phone line has been thrown into turmoil after a supplier pulled out of two contracts for providing the service.
NHS Direct has said it will be unable to provide the phone line in two regions - despite winning the contracts to deliver service.
NHS Direct won 11 of the 46 contracts for the 111 service, but it said it cannot provide the service in North Essex and Cornwall because the contract terms were "financially unsustainable".
In a letter to local health bosses in the two regions, officials said that: "NHS Direct has no option but to exit from the contract. The reason for this is that since the launch of NHS Direct's other 111 services, we have established that the contract terms which NHS Direct had entered into are in fact, financially unsustainable."
The NHS 111 line, which replaced NHS Direct as the number to call for urgent but non-emergency care, has been riddled with controversy since its inception on April 1.
The line suffered many teething problems, with patients complaining of calls going unanswered, poor advice given and calls being diverted to the wrong part of the country. Just a month after its launch medics warned that the "problematic" roll out of the system left many patients not knowing where to turn.
Health officials launched an investigation into the advice line after a number of potentially serious incidents, including three deaths, were linked to the service. Last week the British Medical Association called for an independent inquiry into the "disastrous" roll out of the service.
Nick Chapman, chief executive of NHS Direct, said: "In close discussions with Cornwall and the Isles of Scilly and North Essex commissioners and NHS England, NHS Direct has concluded that it is not possible to mobilise these two NHS 111 services, and NHS Direct will exit from the contracts. The reason for this is that, since the launch of NHS Direct's other NHS 111 services, the trust has established that the contract terms which NHS Direct had entered into are financially unsustainable."
A Department of Health spokeswoman said: "The majority of the country has a good NHS 111 service but we know that there are still problems in a few areas. It is only right that NHS England and the NHS Trust Development Authority both work closely with NHS Direct to help it offer a high quality NHS 111 service."
Health Secretary Jeremy Hunt said the decision was "very disappointing". He said that despite "teething problems" the 111 service was running "fairly well" in 90% of the country - though it could be improved and was under review.