OpenAI announced Wednesday that U.S.-based users can call its artificial intelligence-powered chatbot at 1-800-CHATGPT (1-800-242-8478), while global users can text the number through WhatsApp (META+0.66%) -- making the chatbot "more accessible" "through two familiar channels." To start off, callers will get 15 free calling minutes each month.

The AI startup said it is working on ways for users to authenticate WhatsApp messages with their ChatGPT account to access features such as chatting with images or search, which are currently only available through the ChatGPT mobile app and website.

The launch "came out of a hack week project," OpenAI said during its announcement livestream, and was built "just a few weeks ago."

OpenAI announced the calling feature during its "12 Days of OpenAI" event, which has included product rollouts such as its o1 reasoning model and its AI video generator, Sora, and updates for developers.

Earlier in the multi-day event, OpenAI announced a new ChatGPT subscription tier with access to what it called "the smartest model in the world."

The $200-a-month subscription tier, called ChatGPT Pro, gives users unlimited access to the startup's AI models and tools, including a more advanced version of o1 called o1 pro mode and Advanced Voice. The pro version of o1 uses more compute power to "think harder and provide even better answers," the startup said. ChatGPT Pro will eventually offer more compute-intensive productivity features.

OpenAI also announced earlier that ChatGPT can now recognize objects shown through a smartphone camera or on the screen of a device and respond with its Advanced Voice Mode Feature, which OpenAI teased during the debut of its GPT-4o model in May.