The cause and effect of delays on a videoconference call

Polycom, the leader in the video conferencing marketplace released the Polycom ViewStation and Polycom VSX product for various applications. Certain factors may cause delays in a Polycom video call in the form of frame breaks and possibly audio loss.

When Polycom video products were released, they were all designed to utilize the standard H.323 protocol via IP and H.320 protocol for an ISDN connection. ISDN networks offer a digital point-to-point connection using a digital phone circuit, and usually do not encounter packet or frame loss during a video conference call. More emphasis will be placed on IP connections, as they usually require more attention.
 

When considering video conferencing products for use via an IP network, it must be determined that adequate bandwidth is available for a call. For point-to-point calls, a 384 Kbps per site is required, and it needs to be synchronous. This means that both sites must be capable of sending and receiving a call equally. The standard of 384 Kbps is necessary during a videoconference transmission for thirty-frames-per-second television quality video. This transmission rate is the same for an ISDN connection, as well.
 

The biggest detractor to a videoconference call is a lack of sufficient bandwidth. Make sure the available data circuit, whether it is the public Internet or a private network, is not at capacity before beginning the videoconference call.
 

It is recommended that an organization have DSL or cable modem service on-site and dedicated to for their video conferencing systems. This line should be separate from the data network, to prevent them from competing for available bandwidth. Ensuring a quality video conference call is worth the additional cost incurred by utilizing a commercial grade DSL or cable modem connection.
 

If a public Internet connection is being used for a videoconference, it is suggested to assign a static IP address to the Polycom video product. This ensures that the NAT on the network will not need to be transversed, which can  cause connection problems for users attempting to call your organization’s device. If a Polycom video product must be placed behind a NAT, the port ranges will need to be configured for forwarding. This process is described in the Polycom users’ manual.
 

Finally, make sure that low latency is under 100ms during the videoconference connection; this should eliminate packet and frame loss during a call. Knowing the basic requirements for a video conference call, and adhering to them will ensure a productive and successful video conferencing call for your organization.