Telecom hopes its latest problem with its XT mobile network will be fixed by Saturday morning.
The major fault, which occurred about 11am on Wednesday, initially affected tens of thousands of Telecom customers south of Taupo. Most had coverage restored that evening.
However, many customers in the lower South Island were still unable to place or receive calls on Friday night.
The areas affected include Dunedin, Timaru, Invercargill, Queenstown, parts of rural Southland, Otago and South Canterbury.
Telecom chief executive Paul Reynolds told Checkpoint he was confident all cell sites would be fixed by Saturday morning.
It is the second time a major fault has knocked out large parts of the network south of Taupo since December.
Dr Reynolds says compensation for customers "significantly affected" by the latest fault will be announced next week.
He says the situation is unacceptable and there will be an independent review of the XT network.
Dr Reynolds has said the problem was caused by a piece of hardware which developed a signalling problem and began to degrade service on the network. Technicians in New Zealand, China and France were diagnosing the problem.
The Government says compensation may be appropriate following the latest network failure. Communications Minister Steven Joyce believes that, given the competitive market, Telecom will want to make amends.
"They will obviously have to weigh up the fact that they have caused significant disruption to some of their customers.
"And because they are operating in a business environment, I'm sure they'll want to ensure that they look after those people that have been inconvenienced."
Jordan Mauger, of Christchurch, has set up an anti-Telecom Facebook group which has attracted more than 1000 members.
He says it is appalling that his father and others whose businesses use the XT network have to suffer through the ill-management of the network.
Organisers of the New Zealand Masters Games, which begin in Dunedin on Saturday, are considering switching from Telecom as a result of the XT failure.
The manager of the Games, Aaron Joy, says he has been unable to contact key people, making it very difficult to co-ordinate an event featuring 6000 people.
Competitors report sales surge
Telecom's competitors say they are reaping the benefits of its woes.
Vodafone spokesperson Paul Brislen says its stores have reported a surge in the number of customers wanting to change providers, though he could not give an exact number.
He says the latest Telecom XT network fault initially caused a huge amount of traffic to transfer to the Vodafone network, but that has since settled down.
Market newcomer 2degrees is also reporting an increase in sales online and in retail stores.
The Telecommunications Users Association does not think the XT network fault will ultimately affect Telecom's chances of getting a contract to help build a $1.5 billion broadband service.
The association's chief executive, Ernie Newman, says the faults do not reflect on Telecom's technical capabilities and it may be that they have been let down by a third party.
Companies had until Friday to submit their final proposals to the Government on what is seen as a key infrastructure project.