Spark says it appears mobile text, data and voice services have returned to normal on its network.
Earlier it said its mobile phone customers all over the country were having trouble making calls, sending texts or using mobile data.
It said the problems started about 4 o'clock this afternoon and were worse in the upper half of the North Island.
Spark said the situation appeared to come right around 9.30pm and it will continue to monitor the network closely overnight.
The company hasn't said what the cause of the problem was.
Spark also said some customers in the Wellington region were without broadband because of a failure of the Chorus network.