Two leading mobile carriers, SK Telecom and KT Corp., said Thursday they would begin selling used smartphones at outlets across the nation in the upcoming months.

KT plans to sell used smartphones online and offline starting in March and its rival SKT expects to offer used smartphones at the firm’s outlets a month later in April.

KT is also planning to devise a discounted monthly payment plan called the “green sponsor” policy in May to give further assistance to used phone purchasers, according to a KT official.

“The policy is being designed to upgrade the convenience of our customers and as a method to recycle resources,” said a KT official.

Its rival SKT has been marketing used phones on its online store since last July, however, it is the first time either telecom will sell the phones at their offline sites.

“We have found the demand for used mobile phones to be very high after we began selling them at our T smart shop last year,” said an SKT official. “As an initial step, we will market them at the stores run by the company and then widen the effort to all outlets nationwide as soon as we get the necessary units.”

The monthly units of used smartphones sold on its online site ― such as Galaxy S and iPhone 3GS ― jumped to 14,000 units in December, up from 150 units in July of last year.

The company is looking into drafting a discount monthly payment plan for the owners of old phones.

The marketing of old smartphones will make them affordable to more people. The price is likely to be somewhere between 150,000 and 200,000 won ($133-$178) for a smartphone originally priced from 700,000 to 900,000 won, without a two-year contract.

The move also comes as the Korea Communications Commission, which is the state telecom regulator, is expected to implement a “black list” system for all three telecoms in May.

As part of the new policy, the KCC is advising the telecoms to come up with a support plan for those who choose to own a used smartphone.

The black list system enables people to easily switch their mobile phones since they would only have to change the USIM chip. A large distribution chain will be responsible for product quality and after-service, and consumers will be allowed to pick any mobile service provider regardless of the model.

By Cho Ji-hyun (sharon@heraldcorp.com)