Hastings and Bexhill branches of Phones 4u have shut after the firm went into administration.
Four members of staff at the Hastings store and six at the Bexhill branch could lose their jobs.
The firm was forced into administration after its network operator EE decided not to renew its contract leaving the firm without a single network partner.
97 jobs across the 20 stores in Sussex could be lost including those at the Hastings store on Queen’s Road.
Staff were called into work on Monday and briefed about the situation.
It is not yet clear if the stores will re-open for trading or whether a buyer can be found to save the company.
Phones 4u chief executive David Kassler said: “Today is a very sad day for our customers and our staff. If the network operators won’t supply us, we don’t have a business.
“A good company making profits of over £100 million, employing thousands of decent people has been forced into administration.”
PWC were appointed as administrators on Tuesday September 16 and will decide on the fate of the company.
Rob Hunt, joint administrator for PwC said: “This is a very sad day for the business and the many people working there.
“Our initial focus will be to engage with parties who may be interested in acquiring all or part of the business.
“We will also be talking to network operators and suppliers and trying to access funds to pay for the costs of the business, including wages.
“These conversations will determine whether we can re-open stores and trade, and also if and when we can pay the arrears of wages to employees. Our hope is that we will be able to pay all the outstanding wages arrears.”
Customers who bought phones or took on contracts from Phones 4u have been told they will not be affected by the situation.