Gangnam-gu Cracks Down on Phishing With Call Blocking and Next-Gen Text Verification

Gangnam-gu is stepping up protections on phone calls and text messages to prevent voice phishing and smishing attacks that impersonate public institutions.

Starting this month, the district began blocking phishing calls that spoof or alter Gangnam-gu phone numbers at the network level, and introduced a next-generation text messaging service that displays the district's official logo and a trust mark on administrative notices.

On the call-security side, Gangnam-gu is applying the Korea Internet & Security Agency's voice-call blocking service to intercept phishing calls that fraudulently use or alter the district's numbers before they reach residents. The measure stops voice phishing calls impersonating the district office or neighborhood community center numbers from connecting to the public.

The district is also keeping its existing caller-identification feature in place. Since March 2023, Gangnam-gu has run a caller-information notification service that displays the institution name and department name on a recipient's mobile screen whenever the district calls a resident. Where the earlier system focused on making genuine administrative calls easy to recognize, the new blocking capability adds a layer that cuts off spoofed or altered numbers before they can ring through, strengthening the overall call-safety net.

Text messages are also being made easier to verify as official. Gangnam-gu sends an average of about 1 million text messages a month for administrative information and civil-service guidance. As phishing attempts impersonating public institutions — or hijacking district office and community center numbers — have continued, the need to distinguish genuine administrative texts from fakes has grown.

In response, the district added a Rich Communication Services (RCS) next-generation text function to its existing integrated messaging system. When a resident receives an official notice from Gangnam-gu, the district's institutional logo appears on the incoming message screen. Opening the message reveals a shield-shaped trust mark at the top of the screen alongside the text "Verified Sender Number," letting recipients confirm at a glance that the message came from a number authenticated by Gangnam-gu. Tapping the institution logo brings up Gangnam-gu's full official institution profile.

"With voice phishing and smishing impersonating public institutions showing no sign of stopping, it is important to build a protection framework that lets residents check communications from administrative agencies with confidence," Gangnam-gu District Mayor Kim Hyun-gi said. "We will continue to actively apply AI and advanced technology to administrative services to keep residents' daily lives safer."