40142: Conference instruction failed: missing 'call_sid' or 'outbound_to'

This error occurs when you issue a TaskRouter conference instruction for a voice task that is missing the call attributes TaskRouter needs to connect the worker and caller. For inbound voice tasks created through <Enqueue>, accept the Reservation with conference to bridge the worker into a conference with the inbound caller. If you create a voice task manually and want to use conference, include at least call_sid and to in the Task attributes. For outbound voice tasks, include outbound_to in the Task attributes.

• The Task was not created through <Enqueue> for an inbound voice call.
• The Task attributes do not include call_sid for the voice task.
• The Task attributes do not include outbound_to for the outbound voice task.
• The Task was created manually for a voice flow and does not include the minimum attributes required to use conference, such as call_sid and to.

• For inbound voice routing, create the Task through <Enqueue> before accepting the Reservation with conference.
• Review the Task attributes before you issue conference. Add call_sid for inbound voice tasks.
• For outbound voice tasks, add outbound_to to the Task attributes before you issue conference.
• If you create voice tasks manually, include at least call_sid and to in the Task attributes so TaskRouter can execute the conference instruction.

• Task Reservation Resource
• How TaskRouter Works
• Call Control Concepts