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 of outages from about 9am.
Reports of outages ranged from as far south as Dunedin up to Auckland.
Some reports said 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 and all services should now be restored.
"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."
However the telco is still having issues with mobile phones.
"We're really sorry about this, it's primarily because of the volume of devices trying to automatically reregister back onto our mobile network. For customers still unable to connect, we ask them to please be patient. While the backlog is being cleared it is taking some time to get through, and customer mobile connectivity may go on and off intermittently in the meantime," Llewellyn said.
"We apologise again for the hassles this has caused. We are working hard to have everyone back up and running fully as soon as possible."
Paul Brislen from Paymark said most Eftpos terminals wouldn't have been affected by the outage, as they can take off-line transactions.
TradeMe was also unaffected by the outage, however a spokesman said members who's auctions may have been impacted should get in touch with the customer services team.
An update on Spark's Twitter said the outage was caused by "a wee hardware failure."
Update on mobile/broadband issues: Should all be back to normal now - a wee hardware failure which caused issues for people in various 1/3— Spark (@SparkNZ) January 28, 2017
places around NZ. If you're still having issues, rebooting your phone or router should sort it, but DM us your number if this doesnt fix 2/3— Spark (@SparkNZ) January 28, 2017
it and we'll take a look. Sorry to interrupt your weekend, and thanks for your patience! 3/3— Spark (@SparkNZ) January 28, 2017
People on Twitter reported outages in Henderson, Te Atatu, Whakatane, and Wilton.
Spark's outage status map did not report the issues today.
We're aware of issues affecting mobile and broadband customers right now, we're looking into it urgently and will update when we know more.— Spark (@SparkNZ) January 28, 2017
A Vodafone spokesperson said there were no issues with its network.
People contacted the Herald regarding the outage.
A Spark customer said there are "major internet/phone outages".
"We've been down for an hour - can't send texts, call out or anything. Luckily internet is with another provider."
She said she was frustrated with a lack of information about the outages online.
"I thought it was just us."
Another reader wrote: "Spark down in Canterbury. Zero access to anything at all."