Mobile, internet and landline services with the Spark network faced outages around the country this morning.
The company's Facebook page was flooded with complaints from about 9am. Reports of outages ranged from as far south as Dunedin up to Auckland.
Some reports say there are only issues with accessing international sites, which could mean an issue with the Southern Cross cable.
Spark confirmed problems with its network in a Facebook post.
"We're aware of issues affecting some people broadband mobile in various places around NZ right now, we're looking into it urgently and will share more info as soon as we have it. Thanks for sitting tight, we appreciate it."
Spark spokesman Richard Llewellyn said the problem has been fixed.
"From approximately 9.15am there were widespread outages intermittently impacting some mobile and broadband services in locations around the country.
"This impacted 263 of the approximately 1500 Spark mobile sites in New Zealand, those sites predominantly in the Auckland region. Broadband services were also impacted in other locations around the country," he said.
"Technical teams have been working hard on resolving the issues as a matter of urgency. The problem was identified as a hardware fault located in one of the core Spark network exchanges and a fix has been put in place. Most impacted services restored immediately, and others are progressively self-restoring."
Mr Llewellyn said if customers do not see services return to normal, they should restart their modem or mobile.
An update on Twitter said the outage was caused by "a wee hardware failure."
A Vodafone spokesperson said there were no issues with its network.
