Vodafone is to make 375 staff redundant in an efficiency drive, the operator announced on Tuesday.
According to Vodafone, the people going are "primarily in back-office functions" such as admin, human resources and finance. A number of locations will be affected by the redundancies, which will start this month, the operator said.
Vodafone added it will also hire 170 people in new customer-facing roles and a further 50 staff in September as part of its graduate scheme.
"We're committed to increasing the number of customer-facing employees, which will help us simplify our business and continue to deliver outstanding communications services across the UK's best network," Vodafone human resources chief Matthew Brearley said in a statement.
The Communication Workers Union (CWU) said it was disappointed by Vodafone's announcement and suspected that customer-facing jobs could be lost despite the operator's assurances.
"It's regrettable that Vodafone is making these job losses and is certainly bad news for the company's staff," said CWU deputy general secretary Andy Kerr.
"We're not sure that the information coming from the company regarding redundancies is entirely accurate. There are rumours that jobs will be lost from Vodafone sites in Stoke and Warrington and these are both customer-facing operations, while Vodafone has implied that customer-facing roles will be expanded."
Kerr called on Vodafone to detail how its decision would affect staff, give assurances about "a voluntary approach to redundancies", and show a willingness to redeploy staff rather than make them redundant.
As part of its cost-cutting drive, Vodafone announced plans in November 2009 to end its final-salary pension scheme.