Accepts the ringing incoming call. Media starts after the call connected; audioUrl plays once, imageUrl is shown, videoUrl loops as the camera. hangupAfterSeconds, if given, ends the call that many seconds after it connects. Every media URL is fetched before the call is accepted, so an unusable URL fails the request instead of answering a call that then plays nothing. Errors come back as data.status: error with message and explanation. Note: This endpoint is currently in beta and may change without notice.