Telecom has confirmed only 83 out of 640 emergency calls attempted south of Taupo made it through to operators during last month's XT mobile network outage.
The 111 calls failed to get through between 4pm and 11pm on 22 February.
However the company insists its system is safe.
It says a great many of the calls that did not get through were redials by media and engineers who were testing the line during the outage.
The company says almost half of all 111 calls made each year do not stem from genuine emergencies.
Telecom spokesperson Mark Watts says once an attempt is made to put through a 111 call, that number is registered and then called back.
