Trying to get OCI announcements into a channel

There used to by API endpoints to post a message into a channel. I can no longer see it. We'd like to get OCI messages sent to a channel as a message. OCI can send to a custom http url or an sms (but channels don't have numbers) but I can't figure out if there is a URL I can send to for API for this. We could even do via webhooks, but even those options dont seem to all be there anymore.