Repairs have begun on damage to cables caused by flooding at the weekend, which led to broadband and mobile outages, including for medical alert bracelets.
Rangitata River flooding hit Chorus fibre cables which cross the river at two points, on State Highway 1 and 12km away on Scenic Route 72.
Chorus provides broadband for all major providers.
In terms of mobile coverage, Spark was wiped out south of Ashburton.
This is because Chorus and Spark share cables which provide both broadband and mobile coverage.
Other mobile providers have their own lines, including over the third southern crossing point over the river at the KiwiRail bridge.
There was also some lost mobile coverage for 2degrees at the weekend.
The company was unable to pin down the cause yesterday, but it could be a mixture of fibre breakages and power outages.
Chorus stakeholder and communications manager Steve Pettigrew said it was fixing the Scenic Route 72 breakage yesterday as access to the road was reopened, but State Highway 1 remained inaccessible.
It had two points crossing the river for "resiliency", but unfortunately both were hit, he said.
Spark corporate relations partner Arwen Vant said the South Island’s rugged landscape created part of the problem.
"We have to use existing infrastructure, so it’s usually laid alongside roads. When it cuts across a river it needs to go across a bridge."
Coverage was able to be restored before the cables were fixed using a "work-around".
Some fibres within the damaged cables remained intact, so once the problem was located it was able to migrate services over to the non-impacted fibres.
There is currently no fibre route up the lower West Coast of the South Island.
Ms Vant said Crown Infrastructure Partners was investigating the feasibility of building such as route, but it would cost tens of millions of dollars.
It would traverse Wanaka, Hawea, Haast, up the West Coast to Hokitika and across Arthurs Pass.
"Who knows ... even if such a route existed, whether that would have helped."
The outage affected all medical alarm providers.
St John head of telecare Nick Coley said it became aware of the outage on Saturday night and started contacting affected customers to advise them.
"Once we had been advised the outage had been resolved, we had 90 alarm activations, almost all from customers letting us know of any continuing issues they were having."
It had processes in place to contact customers or a designated contact person, he said.
