The Korea Communications Commission is advising domestic smartphone users to temporarily block data roaming services in order to avoid excessive charges while overseas.

The KCC recently announced the caution in advance of a streak of early-May holidays that begin on Thursday.

The commission warned that the fee for the data service abroad are about 100 times higher than fees charged at home.

The KCC added that data fees are charged without users’ knowledge when applications automatically operate to update information, even if users don’t turn them on.

According to the commission, users themselves can turn off the data roaming service on their smartphones or ask telecom operators to do so for free.