Once you accept the call (after you validated that the caller is a member and has unds, with the help of the plugin) the plugin will begin charging.
Let’s say your pay per minute rate, set in in Accounts > Settings > Calls is set at $1.97 / min.
In the first minute of the call the plugin will display that you charged $1.97 .
The second minute > $3.94.
The third minute > $5.93
And so on.
Charging is done by the minute and each minute is charged in advance, when it starts, at second 0.