Spark has apologised over a fault that left some homes and businesses in the central North Island without landlines on Saturday morning.
The phone and internet service provider says a small part of its network went through "degradation of service" before the fault was fixed.
That included residential customers with fibre and some larger business customers.
"Service is now fully restored and we apologise to any customers who were affected," the company said in a statement, following several hours of problems.
Customers had reported not being able to make or receive calls.