Spark's broadband and mobile networks have been restored after widespread network issues, but some data services, including 4G, are still being fixed.
Spark's broadband network was restored earlier today after customers experienced widespread issues.
Hundreds of people took to the telecommunication provider's Facebook page this morning to complain about problems with calls, texts and internet service.
Some said they called Spark's helpline for answers, but waited on hold for hours.
A statement from Spark said 263 of its 1500 mobile sites were affected throughout the morning.
All Spark customers should now be able to make mobile voice calls & send texts. There may still be some issues with 3G data & 4G service 1/3— Spark (@SparkNZ) January 29, 2017
Spark tweeted at 6pm that all customers should be able to make mobile voice calls and send text messages.
"There may still be some issues wtih 3G data and 4G service, which we are working on fixing still," it said.
"If there's no service you can try flight mode or restarting to force your phone to connect, but it may take just a little longer for service to restore."
It thanked customers for their patience.
It said the sites were predominantly in the Auckland region, but broadband services elsewhere in the country were affected.
Spark tweeted at 3pm: "Sorry for the Sunday hassles".
Your patience while this is sorted out, sorry for the Sunday hassles 3/3— Spark (@SparkNZ) January 29, 2017
Spark said earlier today the problem was identified as a hardware fault located in one of its core network exchanges and a fix had been put in place.