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.
Citel PBXgateways are installed at the central PBX location, and EXTenders are deployed at branch offices, call centers, or at home offices over managed IP connections, DSL, cable, or analog circuits