Hundreds of jobs in South Yorkshire and North Derbyshire are at risk after high street retailer Phones 4u collapsed into administration.
The national chain has closed 550 stores while a decision about its future is made.
The news comes after network providers EE and Vodafone cut ties with Phones 4u, which employs 5,596 staff across the country.
The firm has shops, or concessions, in Sheffield on Fargate; two in Meadowhall; Drakehouse Retail Park; High Street, Swallownest and Crystal Peaks shopping centre; Parkgate Retail Park, Effingham Street and Well Gate, Rotherham; Burlington Street, Markham Road, Vicar Lane, Ravenside Retail Park and Langhurst Court, Chesterfield; and Queen Street, Barnsley.
“If mobile network operators decline to supply us, we do not have a business,” said Phones 4u boss David Kassler.
All mobile contracts bought through Phones 4u remain unaffected.
PwC is expected to be announced as administrator.
Phones 4u is majority-owned by private equity firm BC Partners.