Imagine that we have 4 other people listening on the channel that our user is talking on. In a multicast environment, the amount of traffic on your network is a single stream, because the multicast network infrastructure makes sure not to needlessly duplicate traffic to the receiving endpoints. So, whether we have 4 people listening—or 400, or 4,000—we still only have one stream. And that's terrific because it means we can scale our user base without worrying too much about how our network is going to be affected.

Don't forget, though, that this is for a stream representing a single channel. Each additional channel where someone is transmitting will create another stream. So, for example, if we have someone talking on the Alpha channel and another person talking on Bravo channel; we'll have 2 streams on the multicast network. If someone talks on Charlie at the same time; we'll have 3 streams (and so on).

In a multicast environment, the number of streams (and therefore bandwidth utilization) is directly proportional to the number of people speaking.