Telstra will axe 650 jobs from its Sensis business.
The Sensis business comprises the Yellow Pages, White Pages and the Trading Post.
The Community and Public Sector Union (CPSU) has strongly condemned the move to sack hundreds of workers.
"Sensis staff have been crushed by the scale of these cuts for a company that is part of Telstra which earlier this month posted record half year profits of $1.6 billion," CPSU national president, Michael Tull, said.
The union claimed it has been requesting from Telstra for more information about the future direction of the company over the past few months.
"It is no secret that Sensis has been struggling so they should have had the decency to tell staff what is going on rather than dropping this bombshell on them today. Sensis staff have done everything they can do to improve the health of this company, so they deserve to be treated better," Tull said.
He added that the union will be looking to ensure that members get their full rights and entitlements during the process and will request Sensis to talk to staff about redeployment across Telstra.
In its financial results for the half year ending December 31 last year, Telstra announced that Sensis will be transitioned to a digital model following its revenue decline.
Sensis performance for the half year was down 12.6 per cent to $479 million.
Its print revenues declined from $280 million to $202 million -- by 27.9 per cent. Individual revenue declines include eight per cent for the White Pages and 22 per cent for the Yellow Pages.
It attributed decline in other avenues to lower call volumes across all voice products.
Telstra chief financial officer, Andrew Penn, said the performance for the half year was "in line with expectations".
"We do expect the margin to decline year on year with the revenue reduction," he claimed.
At the time of publication, Telstra has been contacted for comment.
More to follow.
Sign up for CIO Asia eNewsletters.