User guide

Chapter 4 – Configuring Your MultiVOIP
MultiVOIP® Voice/Fax over IP Gateways 57
H.323 Call Signaling Parameter Definitions.
Field Name
Values
Description
Use Fast Start
Y/N
Enables the H.323 Fast Start procedure. May need to be enabled/disabled for
compatibility with third-party VOIP gateways.
Signaling Port
port
Default: 1720 (H.323)
Register with Gatekeeper
Y/N
Check this field to have traffic on current VOIP gateway controlled by a gatekeeper.
Allow Incoming Calls
Through Gatekeeper Only
Y/N
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
1 and 2
--
A first and a second alternate gatekeeper can be specified for use by the current 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).
Gatekeeper Name
alpha-
numeric
Optional. The name of the GateKeeper with which this MultiVOIP is trying to 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 expires and the gatekeeper no longer permits call traffic to or from that
gateway. Calls in progress continue to function even if the gateway becomes de-
registered
Gatekeeper Discovery
Polling Interval
integer
60 - 300
The interval between the VOIP gateway’s successive attempts to connect to and be
governed by a higher level gatekeeper. The Primary GK is the highest level gatekeeper.
Alternate GK1 is second; Alternate GK2 is the lowest.
Use Online Alternate
Gatekeeper List
When selected, VOIP seeks an alternate gatekeeper (when none of the 3 gatekeepers shown on this
window are available) from a list. The list resides on the Primary gatekeeper 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 Multiplexing
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 Tunneling (Tun)
Y/N
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, is the client and who is 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.
Parallel H.245
(FS + Tun)
Y/N
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.
Annex –E (AE)
Y/N
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).