South Korea’s largest cryptocurrency exchange Upbit said it is deactivating the accounts which have no trading records for the past six months.

Upbit said the deactivation is to protect investors from hackers and voice phishing. Before deactivating, Upbit will send emails and other notifications to the account holders. It has not said how many accounts have remained idle for the past six months,

Even though they remain deactivated, investors can reopen the accounts when and if they want. As long as these idle accounts are frozen, investors can not deposit, sell, or buy cryptocurrencies and withdraw or deposit local currency, the exchange said,

These idle accounts, classified as Level 1 in security grading, are kept and managed separately from the active accounts, the exchange added,