GPT-5.5 Instant Is Now ChatGPT’s Default Model What Changes for You
Quick Answer OpenAI replaced GPT-5.3 Instant with GPT-5.5 Instant as the default model for all ChatGPT users in early May 2026. The new model delivers 52.5% fewer hallucinations on high-stakes topics, smarter automatic routing between fast and deep reasoning modes, and arrives alongside three dedicated real-time voice models that bring GPT-5-class reasoning to live voice,…