The major fault in Telecom's new XT mobile network continued to affect thousands of customers in the South Island on Thursday.
Tens of thousands of customers south of Taupo were unable to access the mobile phone network for several hours on Wednesday because of the fault which occurred about 11am.
The majority of customers had coverage restored by Wednesday night but an estimated 10,000 in the South Island were still unable to access the service late on Thursday night.
In its latest update at 10pm, Telecom says customers in Dunedin, Invercargill, Timaru and Queenstown still cannot place or receive calls, while XT users in other areas are still experiencing intermittent service issues.
Telecom chief executive Paul Reynolds says the problem was caused by a piece of hardware which developed a signalling problem and began to degrade service on the network.
Technicians worked throughout Wednesday night to try to restore service. Teams in China and France were also helping to diagnose the problem.
However, Dr Reynolds is angry about the failure and admits the network's recent performance isn't good.
"I'm absolutely livid for our customers - this is the second time in two months we've had significant problems - and on both occasions it's been in the area south of Taupo."
Dr Reynolds says compensation claims will be looked at closely, but only after the network is fixed. He has commissioned an independent review into the matter.
Meanwhile, rescue services say lives could be endangered by the failing XT network.
The Rescue Co-ordination Centre says people who need emergency help could be hindered, while Queenstown harbourmaster Marty Black says the lakes are particularly busy at this time of year and he cannot be contacted on his cellphone.
This week's breakdown is the second major fault since December and comes less than a year after Telecom launched the XT network.
Consumer New Zealand chief executive Sue Chetwin says it is disappointing for customers who believed Telecom's marketing hype.
The company needs to come up with a compensation offer, she says.
Telecommunications Users' Association says the continued problems with the network are unacceptable and people are losing confidence in Telecom.
Association chief executive Ernie Newman told Checkpoint the latest crash is embarrassing for the company.
"I'm quite sure they'll be asking some questions because they will have very, very red faces. But from the users' point of view, what we need is a robust network - we need to know that we can have faith in it."