Before performing a calculation using the Lines and IP Bandwidth Calculator, you should select the VoIP transmission parameters using three drop down boxes (Coding algorithm, Packet duration and RTP header compression). These are described in the previous section.
Then, click on the radio button associated with either Voice paths or Bandwidth to indicate which quantity is unknown and to be calculated. Enter the known value into the other edit box, which should be white. When you press the calculate button, the unknown quantity (either Voice paths or Bandwidth) will be displayed in the grey box.
You may change the units used to enter and display bandwidth by clicking on the radio buttons to the right of the window. The options are kbps and Mbps.
To start the calculation, press the Calculate button. After a short time, the unknown figure will be displayed in the relevant edit box.