Telstra has slashed more than 40,000 jobs since 1996 and privatisation will lead to more job cuts, according to the Communications, Electrical and Plumbing Union (CEPU).
The union said full-time staff has been slashed from 76,522, as stated in the company's 1995-96 annual report, to 36,159 in 2003-04 as a result of cost pressures.
Since the first bill allowing the sale of one third of the telco, CEPU national research officer Ros Eason said full time staff numbers have been cut by more than half.
But at the same time Telstra has established a pool of about 19,000 contract, casual or part time workers.
Eason could not be specific about job cuts as a result of full privatisation as there has already been such a huge level of rationalisation of staff numbers. She said privatisation could lead to "increased pressure on staff conditions" such as wages and a push towards individual workplace agreements.
Once the government no longer owned a part of Telstra, Eason said the company would not have to bow to political pressures.
CEPU state secretary of the telecommunications branch Len Cooper said the union, which represents about 30,000 Telstra workers nationally, was concerned about significant job shedding as a result of privatisation and is planning a national campaign.
Cooper said the campaign will be launched before xmas aiming to force the federal government into a national plebiscite over the sale.
The union hoped to get over one million signatures, particularly in rural areas, to petition the matter.
Earlier this week, the National Party signalled it would not stand in the way of the full sale of Telstra.
The coalition will control the Senate from July 1 next year, thanks in part to gains by the Nationals, paving the way for the sale of the government's remaining majority stake in the telecommunications giant.
National party leader in the Senate, Ron Boswell, told parliament there was no rift between the coalition partners on Telstra.
"Now you (Labor senators) try to put some divisive rift between the National and the Liberal party; but you couldn't put a cigarette paper between us," Senator Boswell said.
He said a $1.5 billion boost to rural and regional services had provided a "decent communications system" for the bush. Communications Minister Helen Coonan said the sale would go ahead.