Is turning on Tianyi Assistant a blacklist?

No.

According to the official website of China Telecom, we learned that Tianyi Assistant is a value-added service launched by China Telecom. It mainly provides voice assistant, intelligent response, schedule reminder and other functions to help users manage their life and work more efficiently. Turning on Tianyi Assistant will not block the mobile phone number, but if Tianyi Assistant is set to intercept all incoming calls, then all incoming calls will be intercepted and the mobile phone will not be able to answer incoming calls.