The mast leases expire in 2015 and there are concerns cellphone and broadband coverage at Treble Cone Ski Area and Wanaka township may be degraded unless another suitable site can be found.
The landowner of the present tower site is Auckland real estate broker Greg Marler, who works in Singapore.
Mr Marler told the court in 2005 he would cancel the leases if he obtained resource consent to build a house.
The consent was granted in November and the conditions were confirmed last month.
The visibility of buildings and structures on Roys Peninsula, a designated outstanding natural feature, was a contentious issue during the consent process.
Vodafone external communications manager Matt East said if a suitable alternative site could not be found, it could have a "massive" effect on customers in Wanaka, including those using Treble Cone skifield or Glendhu Bay camping ground.
Mr East said Vodafone wanted to maintain its footprint in Wanaka because it is an important tourism town and because of high-risk recreational activities on the fringes of the Mt Aspiring National Park.
Cellphone coverage does not reach the back country, but some areas just outside the park get cover.
It was important to find a site that was not too close to the mountains, as that could interfere with the range of cover, but "based on the geographical area, there are not a lot of options", Mr East said.
"By losing that [Roys Peninsula] site, some of the town's capacity will be lost.
For example, broadband sticks on computers: the performance would be slightly degraded.
We don't want that to happen."
Mr East said with co-operation from Telecom, just one mast would be needed, which would address any concerns about landscape values.
Telecom media relations executive Ian Bonnar said the company was confident it could find a new site, if required.
"The lease still has the best part of five years to run, and typically we wouldn't start looking for a new site for at least a couple of years more.
This sort of thing does to come up from time to time, as we have more than 1000 sites nationwide and we treat it as business as usual," Mr Bonnar said.
One of the conditions also mentions that mast heights could be lowered in the meantime.
Telecom was not aware of any requirement to do that.
"Our mast at Roys Peninsula is currently operating at the agreed height, which is outlined in our lease, and we have no plans to lower it," Mr Bonnar said.
The costs of new Telecom sites varied but were "roughly" about $300,000 a site, Mr Bonnar said.
Land Search and Rescue Wanaka police co-ordinator Sergeant Aaron Nicholson yesterday said cellphones were being used in the back country to contact emergency services, so any service reduction would be a concern.
Treble Cone operations manager Rosco Davies said the Roys Peninsula masts were an important link in the cellphone network, and he hoped the companies would work together to find a suitable new site.
