Grandstream Networks GXP-2020 NAT Traversal, Subscribe for MWI, Proxy-Require, Voice Mail User ID

	NAT Traversal	This parameter activates the NAT traversal mechanism. If activated (by choosing
		“Yes”) and a STUN server is also specified, the phone performs according to the
		STUN client specification. Using this mode, the embedded STUN client detects if
		and what type of NAT/Firewall configuration is used. If the detected NAT is a Full
		Cone, Restricted Cone, or a Port-Restricted Cone, the phone will use its mapped
		public IP address and port in all of its SIP and SDP messages. If the NAT
		Traversal field is set to “Yes” with no specified STUN server, the GXP-2020 will
		periodically (every 20 seconds or so) send a blank UDP packet (with no payload
		data) to the SIP server to keep the “hole” on the NAT open.
		Default is No. When set to “Yes” a SUBSCRIBE for Message Waiting Indication
	Subscribe for MWI:
		will be sent periodically.
	Proxy-Require	SIP Extension to notify SIP server that the unit is behind the NAT/Firewall.
	Voice Mail User ID	When configured, user can access messages by pressing “MSG” button. This ID
		is usually the VM portal access number.
	Send DTMF	This parameter specifies the mechanism to transmit DTMF digit. There are 3
		supported modes: in audio which means DTMF is combined in audio signal (not
		very reliable with low-bit-rate codec), via RTP (RFC2833), or via SIP INFO.
		Default is No. Use only if proxy supports 484 response.
	Early Dial
	Dial Plan Prefix	Sets the prefix added to each dialed number.
		Default is No. If set to “Yes”, Call transfer, Call Forwarding & Do-Not-Disturb are
	Enable Call Features
		supported locally provided ITSP support those features.
	Session Expiration	The SIP Session Timer extension enables SIP sessions to be periodically
		“refreshed” via a SIP request (UPDATE, or re-INVITE. Once the session interval
		expires, if there is no refresh via a UPDATE or re-INVITE message, the session is
		terminated.
		Session Expiration is the time (in seconds) at which the session is considered
		timed out, provided no successful session refresh transaction occurs beforehand.
		The default value is 180 seconds.
		Defines the minimum session expiration (in seconds). Default is 90 seconds.
	Min-SE
	Caller Request Timer	If set to “Yes”, the phone will use session timer when it makes outbound calls if
		remote party supports session timer.
	Callee Request Timer	If selecting “Yes”, the phone will use session timer when it receives inbound calls
		with session timer request.
		If set to “Yes”, the phone will use session timer even if the remote party does not
	Force Timer
		support this feature. If set to “No”, the session timer is enabled only when the
		remote party supports this feature. To turn off Session Timer, select “No” for
		Caller Request Timer, Callee Request Timer, and Force Timer.
	UAC Specify Refresher	As a Caller, select UAC to use the phone as the refresher, or UAS to use the
		Callee or proxy server as the refresher.
	UAS Specify Refresher	As a Callee, select UAC to use caller or proxy server as the refresher, or UAS to
		use the phone as the refresher.
Grandstream Networks, Inc.		GXP–2020 Users Manual	Page 29 of 33
		Firmware 1.1.4.3	Last Updated: 05/2007