Polycom 6400-S manual Configuring VoIP

Configuring VoIP

Field	Description
SIP Server Address	The SIP server provides
	session-initialization protocol service to IP
	phones, client adapters and gateways.
	If a SIP ALG is needed, enter the address
	(either an IP or URL) for the SIP Server.
	This address should be reached via the
	Provider side Ethernet port.
SIP Server Port	If a SIP ALG is needed, enter a port for the
	SIP Server Port.
Always hairpin SIP media	Normally set to False. If set to True, then
	SIP phone-to-phone calls made on the
	Subscriber side of the 6400-S will always
	have their RTP traffic flow to and back
	from the EP's subscriber interface.
SIP Expires override	The SIP Expires override field specifies
	the number of seconds a registration
	should be valid. The 6400-S uses this
	value to re-write the expires value
	returned from the soft-switch before
	forwarding it to the IP phone. This value is
	used to force the IP phone to register at
	the configured interval And helps to
	maintain NAT bindings in network based
	firewalls when the 6400-S is performing
	NAT/firewall traversal.
SIP Soft-Switch Expires override	The SIP Soft-Switch expires override field
	specifies the number of seconds that
	should be used when forwarding
	registration messages to the soft-switch
	on behalf of the IP phones. This should be
	higher than the rate pacing value,
	otherwise, the soft-switch may consider
	the phone's registration to have expired. If
	this field is not set, the phone's value is
	forwarded unchanged.

5 - 3