AVer EMC1000, User Manual, Page: 10 / 33

8
FAR-END NAT TRAVERSAL
When the SIP client is behind a firewall, EMC1000 may receive private IP addresses in the receive
SDP (for sending the session’s RTP packets). In this case, the packets cannot be sent before the
first packets are received from the cliebt. The system learns the actual public IP address of these
packets and sends the transmitted RTP packets to this address.
Far-end NAT traversal is applied automatically and no setting in needed in EMC1000.
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In order for this topology to work, the SIP clients located behind the local firewall must support
Near-end NAT traversal.
Near-end NAT traversal for SIP clients requires the SIP clients sending their routable (in most cases
public) IP address in their contact information and r-port parameter.