13257: Invalid transcribeCallback URL

Twilio returns this error when the transcribeCallback attribute on the TwiML <Record> verb is not a valid URL. Twilio documents transcribeCallback as a relative or absolute URL that it uses to send an asynchronous POST request when a transcription is complete.

• The transcribeCallback value provided on <Record> is not a valid relative or absolute URL.
• The transcribeCallback value does not conform to the URL format Twilio expects for transcription callbacks.
• A transcription callback URL was supplied for <Record>, but the callback destination was entered incorrectly.

• Update transcribeCallback to a valid relative or absolute URL.
• Verify the transcribeCallback value in your <Record> TwiML before initiating the recording.
• If you use transcribeCallback, also set transcribe="true" on <Record>, because Twilio requires transcribeCallback to be used with transcribe.
• If you do not need an asynchronous transcription webhook, remove transcribeCallback and retrieve the completed transcription later from the Transcriptions resource instead.

• TwiML Voice: Record
• Transcriptions resource