Thanks for all of the replies, glad there is interest.  Here come some 
replies to some stuff:

John R. Dennison wrote:
> 	Rich,
> 	Have you investigated bandwidth utilization requirements
> 	for this?  Assuming full 16 slots of players and lets
> 	say 4 observer slots, with a lot of chatter.
Here's what the Mumble FAQ has to say on that:

    What are the bandwidth requirements?

 From 0.9.1, this is highly variable, and mostly up to the user. With 
top quality, minimum latency and positional information sent, it is 
133.6 kbit/s including the IP and UDP overhead. With 60 ms transmission 
delay, the lowest quality speech and no positional information, it is 
17.4 kbit/s (again with IP and UDP overhead). The default quality 
setting uses 58.8 kbit/s. When comparing with other products, remember 
to compare the total bandwidth use and not just the bitrate of the audio 

There are two parts to tuning the bandwidth; the audio bitrate per audio 
frame (e.g. 10ms) and the amount of frames to put in each packet. Each 
transmitted packet has a overhead of 28 bytes from IP and UDP alone, so 
at the highest transmission rate (100 packets per second), that is 2800 
bytes of data for raw network overhead alone. You should try to find a 
balance that works well for you, but we generally recommend sacrificing 
high audio bitrate for lower latency; Mumble sounds quite good even on 
the lowest quality setting.

There is no way to adjust the amount of incoming bandwidth; you will 
have to have enough to sustain the total amount of speaking players. 
This should be a minor issue; most players these days are on asymmetric 
lines and hence it is only upload that is a bottleneck.

    What sort of bandwidth will I need for the server?

Worst case scenario: Number of users × Number of talking users × 133,6 
kbit/s. With less aggressive quality settings, it's ~60 kbit/s, and the 
bare minimum is 17.4kbit/s. Note that Mumble is geared towards social 
gaming; its quality enables people to talk naturally to each other 
instead of just barking short commands, so the amount of "users talking 
at the same time" can be somewhat higher than expected.

This means that a server with 20 players and 2 players talking at once 
requires 1-3 Mbit/s, depending on quality settings. In the server's .ini 
file, you can specify the maximum allowed bitrate for users as well as 
the maximum number of clients to allow.



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