Diamond Ogilvy, the incumbent, is expected to defend the business against BBDO, the local agency Veil and LG Telecom's in-house agencies Silver Bullet and Wise Bell.
LG Telecom, owned by the LG Group, one of the country's biggest organisations, was one of the first companies to launch a commercial 3G service using PCS technology.
Pitches are expected to take place at the end of this week. Sources said LG Telecom may choose two agencies that would be used in rotation.