Are you saying the call is completing (your phone rings), but you have no audio? If the call is up and audio is missing, it could be a issue with RTP ports (10000-20000UDP, by default). Are you blocking these ports, or do you have a NAT in between?
Broadcast will let you dial off of a file and will allow you to set a pace, but it will not give you the functionality of waiting for a user to become available before making an outbound call. Using the maximum concurrent calls allowed, you might be able to do something.