This may be also related to the recent Korea Communications Commission decision to "let three local mobile operators, SK Telecom, KT and LG U+, charge users extra fees for VOIP applications or block their use entirely" (here).
".. The operator exceeded three million LTE subscribers in mid-November and four million by the end of 2012 [see chart below] .. The deal expands Tekelec’s policy footprint to a new country in the Asia-Pacific region. The company has additional customers in India, Australia, New Zealand and Singapore".
See "KT selects Tekelec’s market-leading policy server for LTE and 3G networks" - here.