The "safety and effectiveness" of the NHS 111 helpline has been called into question by the country's most senior paediatrician.
Professor Neena Modi said there was concerns over whether 111 call handlers - who are not medically trained - should be carrying out assessments, which even a doctor would struggle with over the phone.
And she criticised the process of assessing children without seeing them, as well as the fact that some doctors do not have access to notes detailing a child's medical history.
Professor Modi, who is president of the Royal College of Paediatrics and Child Health, said 111 had been brought in at huge cost without any proper evaluation of whether it was a safe service.
Last month, a report into the death of 12-month-old William Mead criticised GPs out-of-hours services, and a 111 call handler who failed to spot he had sepsis caused by an underlying chest infection and pneumonia.
The report said William may have lived if the NHS 111 call hander had realised the seriousness of his condition or if a medic had taken the call.
Professor Modi said it was currently uncertain whether 111 was appropriate for children, adding that recognising serious illness "gets more and more difficult the younger the child".
She also deplored the decline of GP out-of-hours services, which she said was a "great loss" to the country.
Referring to the fact that some doctors who assessed William Mead over the phone had no access to his medical notes, Prof Modi added: "This should never happen because good medical practice really builds upon the history.
"The first thing a medical student is taught is to take the history, understand the background and then do the examination.
"When we try and take short cuts, things go wrong."
She said 111 assessors also failed to take a detailed history.
She added: "It also comes down to the fact the non-clinical handlers are not doing what a good doctor would do in this situation, which is to take a very detailed past medical history, and to interpret that in the context of the clinical signs that the child is presenting with at that time.
"It's all part of a standard, high-quality clinical assessment and to expect that to happen over a telephone ... you can see why I think there is a question mark over it and why I think it needs to be evaluated."