21605: Maximum body length is 160 characters (old API endpoint)

You receive this error when you send a request to the legacy /SMS/Messages endpoint with a message body longer than 160 characters. If you need to send longer text, use the /Messages endpoint instead. The current Messages resource accepts body values up to 1,600 characters, and SMS content longer than one segment is segmented and billed accordingly.

• Your application is still sending outbound requests to the legacy /SMS/Messages endpoint.
• The message body in the request is longer than 160 characters.
• Your message content is better suited for the current Messages resource, which supports longer SMS bodies and segmented delivery.

• Reduce the message body to 160 characters or fewer if you must keep the legacy endpoint during a migration.
• Update your integration to send outbound messages with the /Messages endpoint instead of /SMS/Messages.
• Review your SMS content for Unicode characters such as emoji or smart quotes, since encoding affects segment size and message cost when you send long messages through the current endpoint.
• If you regularly send longer text, design for segmented SMS or consider send_as_mms when that delivery model fits your use case.

• Messages resource
• How long can a message be?
• Switching from SMS/Messages resource URI to Messages resource URI