Multi-Tech Systems MVP210/410/810-SS Call Signaling Parameter Definitions, Version 4 Options

Chapter 4: Configuring your VOIP

H.323 Call Signaling Parameter Definitions.

Field Name	Values
Use Fast Start	Y/N
Signaling Port	port
Register with	Y/N
Gatekeeper
Allow Incoming	Y/N
Calls Through
Gatekeeper Only

Description

Enables the H.323 Fast Start procedure. May need to be enabled/disabled for compatibility with third-party VOIP gateways.

Default: 1720 (H.323)

Check this field to have traffic on current VOIP gateway controlled by a gatekeeper.

When selected, incoming calls are accepted only if those calls come through the gatekeeper.

GateKeeper RAS Parameters

Primary GK	--	This is the preferred gatekeeper for controlling the traffic of the current VOIP.
Alternate GK	--	A first and a second alternate gatekeeper can be specified for use by the current
1 and 2		VOIP for situations where the Primary GK is busy or otherwise unavailable.
IP Address	n.n.n.n	IP address of the GateKeeper.
RAS Port	1719	Well-known port number for GateKeepers. Must match port number (1719).
		Optional. The name of the GateKeeper with which this MultiVOIP is trying to
Gatekeeper	alpha-
Name	numeric	register. A primary gatekeeper and two alternate units are listed.
RAS TTL Value	seconds	The H.323 Gatekeeper “Time to Live” value. As soon as a MultiVOIP gateway
		registers with a gatekeeper a countdown timer begins. The RAS TTL Value is the
		interval of the countdown timer. Before the TTL countdown expires, the MultiVOIP
		gateway needs to register with the gatekeeper in order to maintain the
		connection. If the MultiVOIP does not register before the TTL interval expires, the
		MultiVOIP gateway’s registration with the gatekeeper will expire and the
		gatekeeper will no longer permit call traffic to or from that gateway. Calls in
		progress will continue to function even if the gateway becomes de-registered
Gatekeeper	integer	The interval between the VOIP gateway’s successive attempts to connect to and
Discovery Polling	60 - 300	be governed by a higher level gatekeeper. The Primary GK is the highest level
Interval		gatekeeper. Alternate GK1 is second; Alternate GK2 is the lowest.
Use Online	When selected, VOIP will seek an alternate gatekeeper (when none of the 3 gatekeepers
Alternate	shown on this screen are available) from a list. The list will reside on the Primary gatekeeper
Gatekeeper List	or one of the Alternate gatekeepers. The gatekeeper holding the list would download that list
	onto the VOIP gateways within the system.

H.323 Version 4 Options

H.323	Y/N
Multiplexing
H.245 Tunneling	Y/N
(Tun)

Parallel H.245	Y/N
(FS + Tun)
Annex –E (AE)	Y/N

Signaling for multiple phone calls can be carried on a single port rather than opening a separate signaling port for each. This conserves bandwidth resources.

H.245 messages are encapsulated within the Q.931 call-signaling channel. Among other things, the H.245 messages let the two endpoints tell each other what their technical capabilities are and determine who, during the call, will be the client and who the server. Tunneling is the process of transmitting these H.245 messages through the Q.931 channel. The same TCP/IP socket (or logical port) already being used for the Call Signaling Channel is then also used by the H.245 Control Channel. This encapsulation reduces the number of logical ports (sockets) needed and reduces call setup time.

FS (Fast Start) is a Q.931 feature of H.323v2 to hasten call setup as well as ‘pre- opening’ the media channel before the CONNECT message is sent. This pre- opening is a requirement for certain billing activities. Under Parallel H.245 FS + Tun, this Fast Connect feature can operate simultaneously with H.245 Tunneling. Multiplexed UDP call signaling transport. Annex E is helpful for high-volume VOIP system endpoints. Gateways with lesser volume can afford to use TCP to establish calls. However, for larger volume endpoints, the call setup times and system resource usage under TCP can become problematic. Annex E allows endpoints to perform call-signaling functions under the UDP protocol, which involves substantially streamlined overhead (this feature should not be used on the public Internet due to potential problems with security and bandwidth usage).

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