Well yes it is Voice (and Video) over IP, but most people take VoIP to mean sending voice calls over the internet for free or for nothing. We can certainly do that, but our recommended solution is to use VoIP on your local LAN and take the calls out through a locally connected ISDN line.

The trouble with VoIP on the internet is there can be quality issues because you are relying on your ISP to carry your voice traffic to the telephone gateway. Most ISPs have a contention policy where you share your connectivity with many other people, and sometimes voice information arrives late or just doesn't get delivered.

This is fine when using TCP/IP to download pages from the internet, as your download just goes slower than normal. But VoIP is time sensitive, and if the packets are late or don't get there on time then the call quality sounds awful. The Voice Server has special mechanisms inside it that ensure that voice traffic has precedence over your own ADSL line, but once it hits your ISP's systems then we have no more control.

That said, we know of many people who use PSTN gateways over the internet with no issues.