I had this question from a large school district down in Florida and the answer is it depends on what aspects of the OCS conference you are using.
Here is a bandwidth breakout of the conference scenarios:
Application Sharing bandwidth:
Peak Bandwidth Measured in Application Sharing changes as available bandwidth changes.
Desktop Sharing and Remote Control bandwidth
Almost the exact same bandwidth requirements as Application Sharing.
VOIP audio conferencing bandwidth
50Kbps to 80Kbps per audio session minimum required
Webcam or RoundTable video bandwidth
Basic webcam 50Kbps minimum to 350Kbps maximum per video session
RoundTable panoramic video doubles this requirement to 100Kbps minimum to 700Kbps maximum per video session.
To view a previously recorded Live Meeting session from a server is around 220Kbps.
Whiteboard and Poll sessions
Very light weight bandwidth requirements
For more information see this whitepaper here.
Other customer questions:
What are the correct antivirus exclusions required for OCS?
I have only seen information around excluding the OCS binaries and databases from antivirus tools.
What do I need to have installed in order to create my databases on a remote SQL server? Do they need to be installed on my OCS server?
You must install the Backward Compatibility Tools on the OCS server in order to instantiate the pool and create the OCS DBs on a remote SQL server. You can download the tools from here.
Will OCS run on 64-bit Windows Server 2003?
OCS 2007 RTM is not supported on a 64-bit Windows Server 2003 or Windows Server 2008. This will change with OCS 2007 R2 as it will be moving to 64-bit only support. More to come in future blogs around this. Here is the official OCS team blog about the switch to 64-bit only OCS.
Will OCS run on Windows Server 2008?
OCS 2007 RTM it is not supported to run on the Windows Server 2008 operating system. This is slated to change with OCS 2007 R2. More to come in future blogs around this.
Can SQL 2005 be 64-bit?
Yes, in fact it is preferred to run SQL 2005 64-bit.
Will OCS run with Windows Server 2008 Active Directory?
Yes, OCS is supported running in a domain that contains Windows Server 2008 domain controllers.