Bandwidth is an issue both for the business user and for the wholesale DID origination provider. Lean packets allow you to operate numerous telephone numbers through a single router, without fighting for access with your other internet-based applications. A lean codec also enables your wholesale DID origination provider, such as IDT, to keep down the cost of sending the call, minimising your bills.
Your fax, phone and greece telegram conference calls will all use different codecs, but to illustrate their advantages and disadvantages we will describe just two that are often used in VoIP.
One called G.711 collects 80 bytes worth of the original sound signal at a time and does this every 10ms (the “sample rate”). It then wraps these into the packets that are used to send information on the Net and dispatches them at a rate of 50 per second. You can work out that each packet needs to carry approximately 20ms of audio for the codec at the other end to reconstruct “real-time” voice. The G.711 codec uses 87.2 Kbps of your broadband while it is doing this.
By way of contrast, the G.723.1 codec takes 20 byte samples every 30ms and sends them in packets at a rate of 33.3 per second. This time, each packet will need to contain roughly 30ms of voice to achieve quality real-time audio, but uses only 20.8 Kbps of your bandwidth.