Rural Connectivity Group spokeswoman Caitlin Metz said work on the tower had been progressing favourably.
"We've got a minimum build of 400 cell sites nationwide and mobile black spots," Ms Metz said.
"Westland, Grey and Buller are in the top 400."
Haast residents have lobbied for years for cellphone coverage, being in the middle of a cellphone black spot from Fox Glacier to Wanaka.
"We've got 26 sites across the West Coast which are expected to be completed by December 2022," Ms Metz said.
The Haast tower was the first to be installed as part of the rural connecting programme around New Zealand.
"It's important for us to make sure everything is right and we'll provide more information available nearer the completion date."
The new tower, which will be based on 3G technology and be upgraded to 4G at a later date, would allow a quicker response by emergency services, texting, calls and web browsing, but not streaming.
It will give coverage to Haast township as well as State Highway 6 north and east for about 3km.
On August 30 last year the National-led government announced a $32 million plan to improve West Coast broadband and cellphone coverage. In March this year the Labour-led Government committed to implementing that plan.
When it was announced areas listed for improved cellphone coverage were Jackson Bay, Bruce Bay, Jacobs River, Okuru, Okarito Lagoon, Lake Wahapo, Lake Paringa, Haast, Pukekura, Lake Kaniere, Lake Mahinpua, Rapahoe, Charleston and the Buller Gorge. Ultrafast broadband will be extended to Fox Glacier, Franz Josef, Blackball, Carters Beach and Dobson.
