The phone number is built using OpenAI's Realtime API, and the WhatsApp feature is powered by GPT-4o mini through an integration with the WhatsApp API.

OpenAI sees this feature as an important stepping stone for newcomers to AI, since the service represents a simplified version of ChatGPT compared to its web-based counterpart and offers a "low-cost way to try it out through familiar channels." The company notes that existing users seeking more comprehensive features, higher usage limits, and personalization options should continue using their regular ChatGPT accounts through traditional channels.