WebRTC softphone integration failure with ServiceNow screen pop via Data Action

Is it possible to trigger a ServiceNow screen pop via a Data Action when a WebRTC session initiates? The webhook payload arrives at ServiceNow, but the media_type field is missing in the JSON. The Architect flow uses conversation:created but seems to lack WebRTC-specific attributes. Config below:

event: conversation:created
actions:
 - type: webhook
 url: https://dev.service-now.com/api/webhook/gc
 headers:
 Authorization: Bearer <token>

The payload only contains id and type. How to capture the WebRTC channel details for accurate ticket creation?