RealPresence Collaboration Server (RMX) 1500/1800/2000/4000 Administrator’s Guide
Polycom®, Inc. 547
This is necessary because port mappings in the firewall are kept open only if there is network traffic in both
directions. The firewall will only allow UDP packets into the network through ports that have been used to
send packets out.
By default the Collaboration Server sends a FW NAT Keep Alive message every 30 seconds. As there is no
traffic on the Content and FECC channels as a call begins, the firewall will not allow any incoming packets
from the Content and FECC channels in until the Collaboration Server sends out the first of the FW NAT
Keep Alive messages 30 seconds after the call starts.
If Content or FECC are required within the first 30 seconds of a call the FW NAT Keep Alive Interval should
be modified to a lower value.

To enable and modify FW NAT Keep Alive:

FW NAT Keep Alive is enabled in the New Profile - Advanced dialog box.
»Select the FW NAT Keep Alive check box and if required, modify the Interval field within the range
of 5 - 86400 seconds.
System Configuration in SBC environments
In an environment that includes SAM (a Polycom SBC), to ensure that a RealPresence Mobile endpoint can
send content to a conference the value of the system flag
NUM_OF_INITIATE_HELLO_MESSAGE_IN_CALL_ESTABLISHMENT must be set to at least 3.
For more details on modifying the values of system flags, see Modifying System Flags.