Call waiting with “Caller ID” uses a special signal in
order to warn you about an incoming call, during another call there are shown the
name and number of the calling subscriber on the display. The function also
allows switching between two calls.
Asterisk 1.6 emerged with the several features of version 1.2 and 1.4, and also it features new dial plan functions. Further is the list of the recent updates on functionality changes.