Workers at telecoms firm TalkTalk were said to be "shellshocked" today after the company announced the closure of a call centre and other plans to cut jobs.
Consultations opened on plans to close the site in Northampton under moves to "simplify" the company's operations and infrastructure.
The changes will result in jobs being created in some locations and business areas while collective consultations on job losses will begin in other parts of the company, said TalkTalk.
The plans affects up to 390 employees in Northampton, Preston and Warrington.
The Communication Workers Union said 168 jobs in customer retention and sales would be lost at the Northampton site, adding that it understood the company intended to offshore work to Manila and India.
Around 70 staff in Warrington and a number in Preston have been put on 90 days' notice, said the union.
Deputy general secretary Andy Kerr said: "This is terrible news for TalkTalk staff, especially those based in Northampton who will be unlikely to relocate hundreds of miles for other jobs.
"We are also concerned about the move to outsource so many roles, either by offshoring or by using Careline in the UK, as it looks to us that this will lead to an erosion of pay and conditions and could affect the quality of customer services.
"Members have been calling us for help and advice this morning and there is a feeling of shellshock among many staff. While it is welcome to see jobs being created in engineering roles, it is unlikely that call centre staff affected by redundancies will be eligible for these roles.
"We hope that redundancies will be kept to a minimum and will be seeking redeployment opportunities wherever possible."
The company said: "There will be significant new opportunities for existing employees at Preston, Stornoway and Warrington, and TalkTalk will be working with affected employees to maximise opportunities to transfer to new roles and thereby minimise job losses in a year that, ultimately, will see more UK roles created than lost.
"It is proposed the Northampton site will close after the restructuring is complete, with approximately 200 new roles created at Preston through the appointment of a new strategic partner to manage the existing site and some of its operations."
The firm added that it will be creating 250 engineering jobs this year to support the roll-out of the YouView TV service.