Retailer Phones4U has been forced into administration it has been reported.
550 standalone stores will be closed putting thousands of jobs are at risk while administrators decide on whether the business can reopen.
The retailer employs 5,596 people across the UK.
David Kassler, chief executive of Phones 4u, said: "Today is a very sad day for our customers and our staff. If the mobile network operators decline to supply us, we do not have a business.
"A good company making profits of over £100m, employing thousands of decent people has been forced into administration. The great service we have provided should have guaranteed a strong future, but unfortunately our network partners have decided otherwise.
"The ultimate result will be less competition, less choice and higher prices for mobile customers in UK."
Stefano Quadrio Curzio of BC Partners, Phones 4U's private equity owner, said: "Our overriding concern is for all the dedicated hard-working employees of Phones 4u at a time of uncertainty for the company.
"Vodafone has acted in exactly the opposite way to what they had consistently indicated to the management of Phones 4u over more than six months.
"Their behaviour appears to have been designed to inflict the maximum damage to their partner of 15 years, giving Phones 4u no time to develop commercial alternatives.
"EE's decision on Friday is surprising in the context of a contract that has more than a year to run and leaves the Board with no alternative but to seek the Administrator's protection in the interests of all its stakeholders."
The company said the decisions by the two operators had come as a "complete shock", and as a result they had no option but to call in the administrators.