Telecom has confirmed some 111 calls failed during the outage of its XT network earlier this year.
The XT service failed in parts of the South Island on 22 February.
In the event of such a failure, voice calls from mobiles are supposed to be switched to Vodafone's network, but that didn't happen.
Telecom spokesperson Mark Watts says the company would have had to shut down cell sites in the affected areas to allow emergency calls to be made, but that would have created more problems.
He says that landlines were available and that XT customers were still able to text and email.