Channels are the spaces members read and post in (text, announcements, forums). Create them in Community settings > Channels. That admin UI is not the messaging HTTP API.
List integration channels returns the channels the API key can see.If the list returns 503, retry with bounded backoff, then call Get Messages once you have a channel_id.Channel create, update, and delete HTTP routes live under Legacy. They are not mounted on https://api.returning.ai. Do not use them.
An iframe channel displays an external https:// page or iframe snippet inside the community. Setup: Iframe.Iframe is not send-message. The listener payload is for the embedded site. Look members up with Get User Data when you need a durable profile.