Wet weather has caused faults in the Chorus copper network, leaving Spark customers without broadband and phone connections in some areas.
Spark said it had experienced over 6000 fault related calls per day this week, an increase of 30 per cent compared with a few weeks ago.
The number of faults that have required a visit by a Chorus technician is close to the number for the entire 2015/2016 summer season, the telco said.
General Manager of Spark Care, Bridgette Dalzell said customers across New Zealand have been affected.
"The sad reality for our customers whose broadband or landline services are delivered via copper, is that the Chorus network is many decades old and highly vulnerable to wet weather. When copper lines get wet or damp, they either stop working or their performance deteriorates badly."
Dalzell said Chorus had warned Spark and other internet service providers that the wait time for technicians to fix the faults could be up to two weeks.
She said Spark wants to see Chorus hire more technicians to deal with the outages.
"Many of our customers find it unacceptable that they have to wait many days or even weeks in today's connected world to get their services back up and running. We agree with them and we're urging Chorus to bring on more technicians."
"While we understand the roll-out of fibre across the country is a key focus for Chorus, no one should forget that millions of New Zealanders still rely on the old copper network and they deserve a better service."
Dalzell said wait times for customers calling Spark were longer than average in recent days because of the surge in faults.
Chorus said it fixes about 34,000 faults on its copper network per month, but received 38,000 faults in June.
Chorus was currently managing about 3000 faults and there were undesirably long lead times in Auckland, Waikato and the Upper South Island.
Chorus General Manager of Infrastructure Ed Beattie rejected the notion faults were connected to the age of the copper network. Beattie said Chorus had invested in the network and it was high quality.
"There is no doubt that heavy rain and lightning has an impact on the copper network, but each year Chorus has a plan in place to deal with the increased workload during the winter months and we share this plan with all internet service providers," Beattie said.
A property developer had cut through and damaged the copper line in Auckland this week, causing an outage that affected 1600 people, he said.
"We have a number of initiatives underway right now to help deal with the winter fault increase, including recruiting more technicians."
He encouraged anyone that was experiencing an outage to report the fault to their internet service provider as quickly as possible.
Earlier this week, the family of Rani Tandon, 87, told the Herald they were "worried senseless" because the elderly woman's medical alarm wouldn't work without a phone line.
The family are Spark customers and a fault in the copper network that had lasted over a week had left the family without a phone.
Their outage was due to be resolved today.