31206: Rate exceeded authorized limit.

Error 31206 is returned by Twilio Programmable Voice when the client's request rate exceeds the authorized limit. It appears in the Voice error catalog and the Voice SDK error set as an authorization error described as the request rate exceeding the allowed limit.

• Your application is making Voice SDK operations in rapid succession so the request rate to Twilio's Voice platform exceeds allowed limits, triggering this authorization error.
• Bursts of outbound call starts that exceed Twilio's documented throughput can lead to rate limiting during voice operations, for example the default 1 call per second outbound rate noted in Twilio Help.
• If your workflow mixes SDK actions with REST API calls, concurrent API activity may also be throttled by Twilio platform protections, which can surface as rate limit errors in client flows.
• When using Voice SDK Call Message Events during a call, sending many messages in a short interval can contribute to hitting platform limits for messaging over the signaling channel. Ensure this feature is used only on active calls.

• Throttle or queue Voice SDK operations such as initiating connections or sending call messages to keep request rates under platform limits. Implement client‑side pacing to avoid bursts.
• Apply retry policies with exponential backoff for actions retried after a rate event to prevent immediate re‑saturation. Twilio recommends backoff when encountering platform rate limits.
• If you require higher sustained throughput for voice calling, engage Twilio to request a throughput increase as documented in Help Center guidance on call limits.
• Use Twilio debugging tools to verify and monitor rate errors in real time, including the Debugger, Error Logs, or a Debugging Events Webhook, so you can identify the specific operations that are exceeding limits and adjust accordingly.
• For Call Message Events, send messages only while a call is active and avoid rapid‑fire messaging patterns to reduce the likelihood of rate issues on the signaling channel.

• Voice SDK Call Message Events
• Debugging your Twilio application
• Sending and Receiving Limitations on Calls and SMS Messages