Union Connect said it expected the number of redundancies at Vodafone UK to top 600.
The network announced at the end of last month that it would cut 500 jobs from its UK operations, including 170 from its Newbury head office. It is part of its strategy to slash £1 billion in annual operating costs by March 2011.
A Connect spokesman said: “The state of play now is that we’re expecting over 600 redundancies in the UK. We are pressing the company to pursue a positive approach to redeployment and re-training wherever possible.
“We have had initial discussions with the company about how it might hope to do this.”
Mobile News understands most of the staff affected are not represented by a union.
However a Vodafone spokeswoman said the company was sticking to its original figure of 500 redundancies. She said: “The figure of 500 hasn’t changed. There are various opportunities for staff to be redeployed. But we will be reducing the amount of jobs at Vodafone UK by 500 regardless of this.”
Vodafone employs 10,000 people in the UK, and 80,000 globally. The latest cuts come after 450 staff were made redundant in March 2008, although many jobs were then redployed.