Hi,
Electrical Engineer here (who designs and specifies) buildings, including NBN and lifts etc.
Its correct that the 3G network is being decommissioned.
If the building was completed in 2020, you will have “fixed lift line” provided by Telstra, but it will be though the fibre NBN equipment. You wont have a physical copper line. The issue with this is if you lose power to the building, you will also lose all telephony services in the building, including the lift emergency phone line. NB: NBN stopped providing battery backup kit with NBN years ago. One as a cost cutting exercise for the NBN rollout. But also in practice the batteries rarely get maintained and are require constant replacement every 3-5 years anyway. The industry has moved to GSM diallers for lifts since 2018.
It is strange that your dialer isn’t 4G compatible. But you can put this down to the original installer going cheapest and putting in a 3G only which would have still been plenty kicking around in 2020. The current contractor may also be looking for an excuse for “extras”. NB: If the dialler is 3G/4G compatible, the you will only have to change to a 4G sim card.
The costs @$2k is around the market rate for replacement. A quick google I have found one company in Sydney that will do for $1750.
You do need to have an emergency phone, but threatening to shut down lifts straight off the bat comes off as a strong arming tactic to me.
If it were my building, I would be looking at the very least getting a second opinion from another lift maintenance company, with a view to changing maintenance contractor long term. Contractors in our building don’t last long if they start threatening the EC with “required upgrades” instead of working with us.
You have until August 31 to change to 4G.
Hope that helps.