The Mumble Protocol is Open Source, just like Mumble itself. The source code for the current version can be found in the Git repository in the file Mumble.proto.
A complete documentation about the protocol can be found here:
UDP Ping packet
Mumble supports querying the following data by sending a ping packet to the target server:
- Timestamp (for measuring the ping)
- Currently connected users
- Maximum users (slot count)
- Allowed bandwidth
An example script can be found at mumble-ping.py.