conference_participant field deprecated; use Conference Insights API

<p>The <b>conference_participant</b> field in the Voice Insights Call Summary is being removed from the <a href="https://www.twilio.com/docs/voice/voice-insights/api/call/details-call-summary"&gt;REST API</a> and <a href="https://www.twilio.com/docs/events/event-types/voice-insights/call-summary"&gt;Event Streams</a> August 1, 2026. This field pre-dated Conference Insights and had limited accuracy due to the complexity of conference call flows. It is currently only populated for calls eligible to participate in a Twilio conference; all others return <b>attributes: null</b>. After removal, all calls will uniformly return <b>attributes: null</b>. Use the <a href="https://www.twilio.com/docs/voice/voice-insights/api/conference"&gt;Conference Insights API</a> or <a href="https://www.twilio.com/docs/voice/voice-insights/event-streams/conference-insights-event"&gt;Conference Insights Event Streams</a> for conference data going forward.</p>