User's Manual
Polycom® RealPresence Collaboration Server (RMX) 1500/2000/4000 Administrator’s Guide
H-4 Polycom, Inc.
Interactive Connectivity Establishment (ICE)
Interactive Connectivity Establishment (ICE) provides a structure/protocol to unify the 
various NAT Traversal techniques that are used to cross firewalls.
It enables SIP based endpoints to connect while traversing a variety of firewalls that may 
exist between the calling endpoint (local) and the MCU or called endpoint (remote). It is the 
only way for remote Microsoft Office Communicator/Lync users to call into the enterprise 
without a VPN.
ICE Guidelines
• Collaboration Server ICE implementation complies with Microsoft ICE 
implementation.
• ICE is available only in IPv4 environment.
• ICE can be implemented in an environment that includes a STUN server and a Relay 
server (for example, Microsoft AV Edge server).
• The firewall must be UDP enabled.
• The Collaboration Server must have a unique account in the Active Directory and must 
be registered with the Office Communications/Lync server.
•From Version 7.8, ICE is supported with Collaboration Server Multiple Networks.
• Ensure that the Collaboration Server system SIP signaling domain has been allowed on 
the Lync Server edge server to which you are federating (if your deployment does not 
include a DMA system).
• Content sharing (BFCP protocol) is not supported in ICE environment.
Connecting to the Collaboration Server in ICE Environment
The dialing methods that can be used by an endpoint to connect to another endpoint 
depends on the ICE environment: Local, Remote or Federation. 
Figure H-2 ICE Environment
Local connection - a connection between the Collaboration Server and endpoints that reside 
within the same organization. For example, an endpoint in Zone A calls the Collaboration 
Server in Zone A.
When ICE over UDP is blocked in the firewall UDP port, the ICE connection through the TCP 
protocol is automatically used instead of UDP for fallback. 










