It is a call which is made over internet protocol (VoIP). For example,
one can call using Google Voice to other recipient located miles away. Such
call can also be international.
Digium Wildcard TE407P card has a built-in hardware echo cancellation, based on a powerful digital signal processor. Board supports E1, T1 and J1 interfaces, which can be configured for each interface or the entire board as a whole.