Efficiency-focused architecture – SK Telecom added three proprietary modifications, including Sparse Gated Attention, that prune irrelevant tokens to make long-context processing cheaper. – SK Telecom added three proprietary modifications, including Sparse Gated Attention, that prune irrelevant tokens to make long-context processing cheaper. SK Telecom has unveiled A.X K2, a 688-billion-parameter large language model that the company is positioning as South Korea’s flagship “sovereign” AI foundation model — a homegrown alternative meant to reduce the country’s reliance on foreign platforms. SK Telecom claims A.X K2 performs comparably to Qwen3.5 and DeepSeek-V4 in reasoning and agentic tasks. The most interesting of the bunch is A.X K2 Raon-Speech, a 21-billion-parameter speech foundation model co-developed with KRAFTON AI.