Text-to-Speech REST API errors - Telnyx

Errors from the Text-to-Speech REST API return an errors array of objects, each with a string code, a title, and a detail. The code values are numeric identifiers but are always JSON strings (for example, "90103"). Validation rejections (invalid provider, missing fields) return schema-level validation errors instead of the codes below.

REST API error codes

Code	Title	Cause
90103	Failed to produce text to speech	The text-to-speech engine could not produce audio. The `detail` mirrors the underlying provider error, such as an invalid provider API key or an upstream availability failure; when the internal error cannot be rendered safely, `detail` is the generic message `An unexpected error occurred, please contact [email protected] if the problem persists.` Contact Telnyx support with the request ID when the detail does not describe a problem in your request.
90104	Failed to list voices	The voice catalog could not be retrieved from the upstream provider. Retry the request.

These codes are scoped to the Text-to-Speech REST API. 90103 also appears in the Call Control surface as “Dials per second limit exceeded”; the two errors are unrelated and share only the numeric code. Check the WebSocket errors page for errors returned over the WebSocket transport.