Web service allowing live streaming of audio podcasts with guest call-in functionality

I am looking for an application which allows one to start live audio (optionally also video) podcasts. A requirement is that this application allows for listening guests to call into the show and be live with the host. Another requirement is a live chat.

The only one I am aware of is blogtalkradio.com but that one is not an option at this time. Are there any other ways? Maybe on YouTube live but I haven’t figured out how to achieve the guest-call-in feature.