Woofun AI reports that Microsoft is accelerating its transition to proprietary AI technology, replacing external models from OpenAI and Anthropic in select applications. Office tools including Excel and Outlook now utilize Microsoft's in-house MAI model for AI requests, processing tens of thousands of calls weekly. While MAI currently represents a small fraction of total AI traffic, its integration into core products marks a significant step toward self-reliance. Mustafa Suleyman, Microsoft's AI lead, has indicated the company's goal to reduce and eventually eliminate spending on Anthropic models. Beyond office software, MAI is integrated into GitHub Copilot, with an in-house speech-to-text model slated for Teams in the coming months. As Microsoft's partnership with OpenAI evolves, the company is strengthening its independent AI capabilities to improve bargaining power and lower inference costs.