Council workers are threatening to strike after being told they must relocate 600 miles from central London to north Scotland or face redundancy.
The call centre is in Belgravia
Unison and the GMB reacted angrily to news that up to 400 posts at a company employed by Westminster City Council are to be transferred to Dingwall.
They work for Vertex in a call centre in Belgravia.
The council said business decisions were down to Vertex but that it was willing to talk to the unions.
Dave Johnson, national officer of Unison, said: "Our members are stunned by the news and very angry. This is pure economic greed at the expense of hundreds of jobs.
Population is 5,000
Calls itself the Viking Capital of Scotland
There were 30 burglaries and 12 thefts from cars last year
Main attractions: Natural heritage including Cromarty Firth
The average house price is £122,908
"It is simply not realistic to expect hundreds of staff to move and uproot their families to live in such a remote area."
Unison said it will be consulting its members over possible strike action.
The GMB said it will challenge the legality of the original contract which outsourced the work from the council to the private company and was not ruling out industrial action in protest at the move.
The affected staff deal with parking, licensing, community protection and library services.
Vertex public sector managing director Andrew Warren said: "Our plans are as they have always been - to deliver excellent services to the citizens of Westminster on behalf of the council.
Population is 220,000
74,391 crimes last year including five murders
Main attractions: Westminster Abbey, Houses of Westminster, West End theatre and more than 2,300 bars or clubs
The average house price is £556,540
"However, these changes are necessary to ensure we continue to deliver these services as cost effectively as possible. We have communicated our intent to our people as early as we could and will continue to support them through this period of change."
A Westminster City Council spokesman said: "We are concerned about the situation, but how Vertex treat their staff, where they locate them and how they run their business is a down to Vertex.
"We are under constant pressure by central government to make savings and provide value for money for our council tax payers and Vertex is responding to this and providing as good a service as possible.
"We have a call centre in Belgravia, when most private businesses are trying to get their call centres out of central London where rent and fixed costs are not so high.
"But we always leave the door open for talks with the trade unions."