Basic Private/Public Networking

In many ways, IP based videoconferencing is similar to telephone systems. Both systems use a number to “dial” the other user. Both can have complex strings of numbers indicating many different things (Country code for example with telephone). To get an understanding, here is a basic analogy of Private/Public networking; which is vital to make/receive calls with IP videoconferencing.

On a network, such as a schools, each device generally has a private IP address. This address is only accessible from the internal network. For example, if I wanted to dial a VC system within my same building I could call a number like this:

– (Call would go through within the local network, and never goes outside of internal building network)
– (Call would go through within the local network, and the “#001” denotes an “extension”, meaning there are more than one system on that particular IP Address)

The above 2 scenarios will most likely never happen within our school district, as most schools/locations only have 1 VC system.

Normal call scenarios are like this:

– (Call goes through internet, to a public IP address available from anywhere. This is commonly used in VC)
– (Call goes through internet, to a public IP address, and then to an extension of “001”. This is used more and more as organizations adopt gatekeepers and adopt a dialing strategy)

The only real difficult part of the last 2 scenarios, is making sure that the endpoint you are calling from, has public internet access in/out. Calling a public address from a private address, the call will connect, but quite likely no video/audio will pass through the firewall on your end.