Polycom 1725-11530-200 Rev A1 manual Network Address Translation nat

Administrator’s Guide - SoundPoint IP / SoundStation® IP Optimization

4.6.2.6 Network Address Translation <nat/>

These parameters define port and IP address changes used in NAT traversal. The port changes will change the port used by the phone, while the IP entry simply changes the IP advertised in the SIP signaling. This allows the use of simple NAT devices that can redirect traffic, but do not allow for port mapping. For example, port 5432 on the NAT device can be sent to port 5432 on an internal device, but not port 1234.

	Permitted
Attribute	Values	Default	Interpretation
nat.ip	dotted-deci-	Null	IP address to advertise within SIP signaling -
	mal IP		should match the external IP address used by the
	address		NAT device.
nat.signalPort	1024 to	Null	If non-Null, this port will be used by the phone for
	65535		SIP signaling, overriding the value set for voIp-
			Prot.local.signalPort in sip.cfg.
nat.mediaPortStart	1024 to	Null	If non-Null, this attribute will be used to set the
	65535		initially allocated RTP port, overriding the value
			set for tcpIpApp.port.rtp.mediaPortRangeStart in
			sip.cfg. Refer to 4.6.1.10.3.1 RTP <RTP/> on
			page 124.
nat.keepalive.inter-	0 to 3600	Null	If non-Null (or 0), the keepalive interval in sec-
val			onds. This parameter is used to set the interval at
			which phones will send a keep-alive packet to the
			gateway/NAT device to keep the communication
			port open so that NAT can continue to function as
			setup initially.
			The Microsoft® Office Live Communications
			Server 2005 keepalive feature will override this
			interval. If you want to deploy phones behind a
			NAT and connect them to Live Communications
			Server, the keepalive interval received from the
			Live Communications Server must be short
			enough to keep the NAT port open. Once the TCP
			connection is closed, the phones stop sending
			keep-alive packets.

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