13201: Dial: Cannot Dial out from a Dial Call Segment

This error occurs when the TwiML returned from a <Dial><Number> url tries to execute another <Dial>. Twilio runs that url on the called party's side after answer and before the call is bridged, and that pre-bridge TwiML cannot contain <Dial>.

• Your application returned a <Dial> verb from the webhook configured in the <Number> url attribute.
• You used the <Number> url webhook to route or transfer the call instead of screening or informing the called party before the bridge. That webhook is limited to TwiML such as <Play>, <Say>, <Gather>, and <Hangup>.
• You expected the called party's pre-bridge call segment to create a new outbound leg directly. <Dial> can only dial a new party from an active call context, and Twilio does not allow that nested <Dial> in this pre-bridge flow.

• Remove the nested <Dial> from the TwiML returned by the <Number> url. Use that TwiML only for called-party instructions or screening before the bridge.
• If you need the called party to hear a message or choose whether to accept the call, return supported pre-bridge TwiML such as <Play>, <Say>, <Gather>, and <Hangup>.
• If you need to continue the original call flow after the <Dial> attempt, move that logic to the parent call by using the <Dial> action URL or the next verb in the original TwiML document.
• If you need to redirect or change a live call asynchronously, update the in-progress call with the Calls API instead of trying to start a new <Dial> from the called party's pre-bridge TwiML.

• TwiML Voice: <Number>
• TwiML Voice: <Dial>
• Call resource