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.
Using Voice over Internet Protocol (VoIP) calling applications on your mobile phone can save you money if you make a lot of international calls or travel out of the country often. iPhone users have several options when deciding what app to download.