HEAnets’ Video Conferencing Service
1.-Principles of Video Conferencing
2.-Elements of a H.323 System
2.2.-Multipoint Control Units (MCUs)
3.-What do Institutions need to get connected to HEAnet's video conferencing
4.-Placing a H.323 terminal on the Network
5.-Security of H.323 service
6.-The Global Dialing Scheme (GDS)
7.-Registering your institutions H.323 terminal endpoint with HEAnet's gatekeeper
8.-Dialling test GDS Numbers
9.-Making a point to point video conferencing call
10.-Making a point to multipoint video conferencing call
11.-Continuous Presence point to multipoint conferences
12.-Private multipoint conferences and chairperson controlled conferences
13.-Dialling HEAnet's gateway (ISDN calls )
Principles of Video Conferencing
The principle of Video conferencing is that a meeting will take place between two or more sites
involving audio and video images. This results in time and cost savings between the
Using your Local Area Network (LAN) and your Wide Area Network (WAN) it is possible to send
these images across the public Internet. This results in further cost savings as most sites
already have a data network in place and there is no need for costly ISDN calls to take place.
The technology HEAnet are using to video conference uses the protocol H.323, this is based on
the more traditional ISDN standard H.320.
An excellent resource for H.323 related technology including video conferencing room design
may be found here.
Elements of a H.323 System
§ Multipoint Control Units (MCUs)
To use HEAnet's video conferencing service an institution only requires one of the four
elements above. Only endpoints are required. All other elements, MCU, gateway and
gatekeepers can be provided by HEAnet's service.
To allow an institute to connect to HEAnet's multimedia services, one must have the required
devices that allow H.323 video conferencing. The basic systems that provide video and audio
images are known as H.323 terminals or endpoints.
HEAnet have tested the following terminals that have been proven to work on our systems.
§ Polycom Viewstation SP
§ Polycom ViaVideo
§ Vcon ViGO
§ Tandberg 550
§ Tandberg 880
§ Tandberg 10 00
There are numerous other endpoints that will also work with HEAnet's services. Generally if
the endpoint supports H.323 it should operate with HEAnet's equipment. If you wish to test if
an endpoint operates with HEAnet's services please contact multimedia
Different endpoints operate at different qualities. The basic way to differentiate between
different quality video conferences is on the speed that the terminal can connect to.
The average speed that H.323 terminals operate is at 384 kilo bits per second (kbps).
Video conference calls between 64 kbps and a 2Mbps are possible. HEAnet recommend that
calls should be made at either 384kbps or 768kbps.
Multipoint Control Units (MCUs)
MCU's allow one to participate in a point to multipoint conference. If more than two sites are
involved in a conference a MCU will be required.
Gateways allow users to convert from older ISDN (H.320) video conferencing to IP video
conferencing (H.323) and vica versa. Gateways also allow GSM and traditional PSTN devices to
be involved in a conference.
Gatekeepers are used for admission control and address resolution of HEAnet's video
What do Institutions need to get connected to HEAnet's
video conferencing service?
§ H.323 terminal.
§ Television. The h.323 terminal connects directly into a display unit such as a TV
system. A large TV system w ill enhance the quality of ones video conference. Please
ensure the sound system is audible to all participants in the room.
§ Lighting system. If a good quality camera system is used most general lighting
systems will be adequate for a video conference. However, direct light onto the local
participants faces will enhance the picture. Please also ensure that reflective surfaces
are kept to a minimum.
§ Furniture, Curtains, backdrop. A backdrop explaining where the video conference
room is located e.g. HEAnet Dublin, Ireland is a good idea in a large conference.
Curtains are used to limit visual reflection and also to dampen sounds. When choosing
furniture please ensure that all participants may be viewed though the camera of the
§ LAN. If using h.323 conferences please ensure that there is no contention on your
network. Packet losses of 5% or more will render your conference unusable. Where
possible please use a switched ethernet design of 10/100 Mbps.
§ Wide area link to HEAnet. To use HEAnet's video conferencing service one must
have a WAN link to HEAnet. For good quality conferences HEAnet recommend at least
a 2Mbps connection.
Placing a H.323 terminal on the Network
Once the endpoint is obtained, one must place it on the premises Local Area Network. utting a
H.323 endpoint on the LAN involves much the same methods as placing a PC on a LAN. A
H.323 endpoint is essentially a PC with a camera and audio features. Therefore all of the
standard trouble shooting procedures should be used to ensure that the endpoint could
connect to the "outside world". Such procedures such as giving the device an IP address,
gateway address and so on are outside the scope of this document.
HEAnet recommend that if possible the video conference equipment is either placed on a
separate LAN or a Virtual one (VLAN) than the institutes main network, this will allow the
institutions to control both the security and the performance of the video conference better.
However, in saying that there should be no issues in placing the endpoint on your standard
Once the standard settings are placed on the videoconference endpoint (IP addresses, subnet
mask, gateway etc.) it should be possible for one to connect out to the rest of the world and
utilise HEAnet's video conferencing services.
First of all check that one may make an IP video conference call to another endpoint. Dial the
following IP address 126.96.36.199. This should make a call to HEAnet's testing device that is
on auto answer.
If one can connect to this endpoint it is now possible to have a video conference call.
Once your H.323 terminal can reach the outside world, three easy steps are required to use
HEAnet's video conferencing service.
1. Ensure that all relevant services are available through your Internet security policy.
2. Get a GDS number.
3. Register with HEAnet's gatekeeper.
Security of H.323 service
Prior to using HEAnet's video conferencing service, there are a number of security issues
involved in allowing H.323 conferencing.
The following ports are a used in H.323 conferencing.
Function Port Type
HTTP Interface 80 TCP
Gatekeeper discovery 1718 TCP
Gatekeeper RAS 1719 TCP
Q.931 Call Setup 1720 TCP
Audio Call Control 1731 TCP
H.245 Control Channel 1024-65535 TCP
RTP ( Video / Audio ) 1024-65535 UDP
H.235 secure signaling 1300 TCP
T.120 1503 TCP
Because H.323 uses dynamically assigned ports it is difficult to control.
Some solutions to overcome this are as follows.
1. Open the ports listed above on your institutions firewall.
2. Use H.323 aware firewalls, e.g. Cisco Secure IS, Cisco PIX, Checkpoint FW-1, Netscreen.
3. Use a separate network for H.323 (H.323 DMZ).
The Global Dialing Scheme (GDS)
To use HEAnet's services one must first understand the Global Dialing Scheme (GDS). The
GDS is a numerical dialing plan that allows H.323 endpoints to dial to remote sites and
services. The GDS uses the same format as telephone numbers (E164) numbers, therefore a
call to the US means that one must dial the prefix 001, UK is 0044 and so on. More details of
the GDS may be found here.
As may be seen from the diagram above there are various numbering levels involved in the
GDS. Each institution has a three-digit number relating to their domain. The following list
gives the details of HEAnet's customers and Institutes of Technologies GDS numbers.
To allow one to use the GDS, one must register with HEAnet's gatekeeper. To register with
HEAnet's gatekeeper follow the points below.
If your institution is not on the list above and would like to subscribe t o the GDS, please
Each institution will be in control of their own GDS number, therefore should TCD who have a
GDS zone number of 121 decide to allocate numebrs, they can do so as follows.
Extension 1. 0035301121 001
Extension 2. 0035301121 002
Extension 3. 0035301121 003 etc………
The rest of the institutes will be the same; Dundalk 0035301114001 and so on.
Please note that one must use full-length numbers when dialing the GDS.
Registering your institutions H.323 terminal endpoint with
1. In your videoconferencing endpoint unit, navigate to the H.323 settings menu.
2. Enter your email address as your endpoint's H.323 Name. This gives the gatekeeper
administrators some idea of who is registering and from where.
3. Assign an E.164 number (also called H.323 extension) in the following manner: 00 35301 +
your institute GDS number + your extension number. *
If, for example, your institutions GDS number is 0035301112 and your extension number is
002 (defined by each institutions IT department) your H.323 extension number would be
4. Your endpoint's system may need to be rebooted.
5. Once it's running again, navigate back to the H.323 setting and select the gatekeeper
6. Enter the following IP address: 188.8.131.52
7. Again, your endpoint may need to be rebooted.
8. Congratulations. You should now be registered with HEAnet's Gatekeeper.
You can call the HEAnet Videoconferencing Service for additional information by calling (01)
6609040 or sending an email to firstname.lastname@example.org
The Irish national Gatekeeper is
Dialling test GDS Numbers
Once the three steps.
1. Ensure that all relevant services are available through your Internet security policy.
2. Get a GDS number.
3. Register with HEAnet's gatekeeper
are completed, one can now dial a worldwide GDS number.
To dial a GDS number ensure that you are dialling out through the H.323 system on your
terminal (called an IP call on some terminals). Then simply enter your GDS number and dial!
A test GDS number to use is 0035301101006 (in HEAnet's) office.Another test GDS number
is "copy bird" in the University of North Carolina in the USA. Dial 00112971216 to connect
to "copybird" and hear and see your own image.
Once you have confirmed that you can dial the above GDS numbers you can now dial any GDS
number and use HEAnet's videoconferencing services.
HEAnet encourage people to advertise their GDS numbers as publicly as possible, e.g. web
sites and email signatures. Only with awareness within the community will the system be
Making a point to point video conferencing call
To make a point to point (only two locations involved) videoconference, one simply needs to
know the GDS number of the remote location.
Once the GDS number is known, simply enter the GDS number in your destination field and
dial. On some systems, in particular Tandberg devices one must ensure that you have the
Network Profile set to LAN or IP call.
It is also possible to make a IP video conference call by entering in the IP address of the far
site, however this is not a scalable solution and to ensure that H.323 systems can expand in
the future, it is recommended that GDS numbers are used.
Making a point to multipoint video conferencing call
As already mentioned in this documentation to set-up a call with three or more destinations
involved will require an MCU device. HEAnet currently have a high specification Radvision MCU
that will allow upto 70 locations participate in a conference. Setting up a multipoint conference
involves one dialling a GDS number. At this point please ensure that you can dial GDS
numbers by testing to these numbers.
When thinking of multipoint conferences try to think of dialling a "virtual room" where
everyone meets. This "virtual room" therefore must have a GDS number to allow one to ring
it. Each member of HEAnet has its own "virtual room" based on its GDS number. For example
Trinity College Dublin has the GDS extension number of 122.
To dial TCD's "virtual room" simply dial the GDS number 003530110062122 To dial your own
institutions "virtual room" replace the 122 numbers with your own institutions GDS extension.
When organising a multipoint conference, one must decide in whose "virtual room" all parties
are to meet. Once this is decided in advance all parties dial that institutions "room". For
example if DCU, UCD, TCD and IT Carlow decide to meet in Trinity's "virtual room", at the
designated time all four institutions dial the number 003530110062122.
The "virtual room" number 003530110062122 is designed as a conference for terminals
connecting at a speed of 384kbps. Other connection speeds are available. For example if
Trinity wanted to set-up a conference at a lower speed e.g. 128kbps, the Trinity "virtual room"
for a 128kbps call is 003530110063122.
The following speeds are available for HEAnet members.
003530110062122 384kbps conference.
003530110063122 128kbps conference.
003530110064122 768kbps conference.
Please note that in all the GDS numbers above one should replace the 122 number with your
own individual Institution GDS number.
All of the multipoint conferences mentioned above are using a technology known as, voice
switched conferencing. This allows members of a multipoint conference to view the person
who is currently talking. For most meetings this type of conference is the most suitable.
However it is also possible to have a second type of conference known as continuous
Continuous Presence point to multipoint conferences
In voice switched conferences just one image at a time is displayed on the screen. However
with continuous presence it is possible to view four locations at once.
Continuous presence conference Voice Switched conference
To set-up a Continuous Presence conference simply dial the following GDS numbers.
003530110074122 384kbps conference.
003530110072122 128kbps conference.
Again the example above is for Trinity College Dublin's "virtual room". Please replace the 122
number with your own individual Institution GDS number.
Private multipoint conferences and chairperson c ontrolled
To set-up a password protected multipoint conference or chairperson controlled conference
one must fill out the following details and send the results to noc or multimedia in HEAnet.
Name of Conference: (e.g. TCD_7_4_2003)
Administrator of Conference
(Details of this may be found here)
Date of conference:
Time of conference (GMT time):
Number of locations in conference:
Required speed of conference: (e.g. 128kbps, 384kps, 768kbps)
Continuous Presence conference: YES/NO
(Please note Continuous Presence is only available ate 128kbps or 384kps)
Please fill out the following if Chairperson controlled conference is required.
Chairperson of Conference
IP Address of desktop where control of conference will take place
Dialling HEAnet's gateway (ISDN calls)
Traditionally video conferencing has taken place over costly ISDN lines. HEAnet are using IP
calls H.323 for video conferencing.
To make legacy ISDN calls you can dial the HEAnet gateway and then be routed through to
the IP network.
To dial into our Gateway simply dial 01 4490889 (if within the Republic of Ireland). After
approximately 6 rings the gateway will answer. You will then be asked to dial a GDS number
followed by the # sign.
Some of the older video conferencing units do not have the ability to dial number strings when
the gateway answers. If this is the case it may be possible under the circumstances for
HEAnet to call your remote site. Please contact email@example.com for further details