The Immigration Office of the Ministry of Justice has announced to beware of the following voice-phishing, especially for foreigners living in Korea. 

If there's a call with unidentified numbers such as 1533-6715 or 1533-6725 or any other similar numbers, impersonating the immigration office, please note that it should be a voice-phishing. Therefore, you must NEVER provide your personal information!  

In such cases, it might naturally connect to an ARS(automated response system) asking you to press '0' and afterward your personal information. Be extra wary of tricks!