Mobile phone giant Vodafone has confirmed it is closing a Birmingham call centre where 650 staff work.
The call centre's work will transfer to Warrington and Stoke-on-Trent
In a statement the company said the Brindleyplace site would close in early February.
"These proposals will result in approximately 650 roles being put at risk of redundancy at the site," the statement said
Some 500 jobs will move to other sites and there may be other jobs people can apply for, the statement added.
Staff heard the news at a meeting at Brindleyplace on Tuesday afternoon.
Union officials said Vodafone could have handled the situation better.
A spokesman for Connect said: "Staff have suspected the site is likely to close but have been left in the dark about their future.
"Vodafone has a history of poor consultations with employees when introducing change.
"For a communications company, when it comes to talking to staff about changes, Vodafone have been surprisingly silent."
The call centre's work will be transferred to centres in Warrington and Stoke-on-Trent.
Vodafone's UK's consumer customer management director Jane Hext said: "We are aware of the effect this decision will have on the team in Birmingham and we will be doing all we can to work with them in the coming months to help them through this difficult period."
The Birmingham Chamber of Commerce said it regretted the job losses especially as it was in one of the newer industries which had become increasingly important since the decline in manufacturing.
Kalim Ilyas, a network advisor who has been with the company for a year, said rumours had been rife for three months.
"I was hoping to move up the ladder and progress in this company but that's been blown out of the water.
"I've got a mortgage, a son, a wife and I can't move to Stoke, it's too far.
"How can we work for another four months with the same motivation as before."
Aman Kang, employed in the customer complaints department, said "Vodafone are saying they can give us alternatives, that we can go to other sites, but we can't go from here to Stoke-on-Trent, that's too far.
"There's no alternative in Birmingham to compensate all 600 of us."