Communications and Information Technology Minister Steven Joyce has asked his officials to investigate options for emergency 111 calls to receive priority if mobile networks became unstable.
The Government might need to regulate to ensure that happened, he said.
Telecom is obliged under the Telecommunications Services Obligation (TSO) to provide emergency calling on its fixed network, but mobile phones are not covered by the TSO.
When networks are completely down, handsets are programmed to roam on other available networks to make emergency calls.
But when networks are intermittently down, that might not happen.
That was the case in some areas of New Zealand on Monday night, Mr Joyce said.
"I reiterate the Government's concern over this ongoing issue.
"The simple reality is that Telecom needs to solve this issue and solve it quickly."
Telecom chief executive Paul Reynolds said, "As is standard for most mobile networks, we already have in place a mechanism that enables all Telecom-supplied XT phones to utilise another network in situations where there is no XT coverage.
"Unfortunately, the difficulties we experienced [on Monday] evening meant that coverage was being provided, but voice calls were not getting through."
