> ## Documentation Index
> Fetch the complete documentation index at: https://docs.retellai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude Sonnet 4.5 model replacement (10/29/2026)

> On 10/29/2026, Retell replaces Claude Sonnet 4.5 (claude-4.5-sonnet) with claude-5.5-sonnet. Existing configurations will be automatically migrated.

* The following models are being deprecated and replaced with newer versions:
  * **Claude models:**
    * `claude-4.5-sonnet` → replaced with `claude-5.5-sonnet`
  * On 10/29/2026, existing configurations will be automatically migrated to the replacement model.


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