Call waiting
Call waiting(orcatch phonein Japan), in telephony, is a feature on
some telephone networks. If a calling partyplaces a call to a called
partywhich is otherwise engaged, and the called party has the call
waiting feature enabled, the called party is able to suspend the
current telephone calland switch to the new incoming call (typically,
this is done by pushing the flashbutton), and can then negotiate with
the new or the current caller an appropriate time to ring back. Call
waiting, then, alleviates the need to have more than one line for
voice communications.
Star codes
For more details on this topic, see Vertical service code.
In North America, the NANPuses the *70 star codebefore a call to
suspend call waiting for that call. A stuttered then regular dial
toneconfirms the de- activation.
On most European telephone networks, and GSMor UMTSmobile phones, call
waiting is activated by dialing the following codes:
*.To activate: *43#
*.To deactivate: #43#
*.To check status: *#43#
A voice announcement, tone or a message on your phone's screen will
confirm the service status.
Call waiting in Europe uses an "R" (recall) button on the phone. This
performs a similar function to a North American hook flashbutton but
is much shorter duration, typically 80ms to 100ms, vs. 250ms in North
America. In some networks, pressing R toggles between the calls,
similar to North America. However, in most countries there are further
options:
*.R1 – Answer the waiting call and hang up on the current call.
*.R2 – Toggle between the calls.
*.R3 – Merge the two calls for conference calling.
*.R0 – Reject call waiting – This will send the call to voice mail or
a busy tone.
Type II Caller IDalso works with call waiting.
Line sharing
Since the waiting call creates an audible signal (for example, a 440
Hzbeep every ten seconds in North America), call waiting can cause
dial-up Internet accessconnections to terminate, unless the
modemsupports the most recent V.92modem standard. For this reason,
call waiting is often disabled on shared voice/ datatelephone lines.
History
Call waiting was introduced to North America in the early 1970s when
the first generation of electronic switch machines built by Western
Electric, Electronic Signaling System 1 started to replace older
mechanical equipment in the old Bell Systemlocal telephone companies.
At first, some smaller municipalities had it only on a specific phone
exchange (e.g., phone customers in Trenton, Michiganinitially had to
have a phone number starting with 671 to have call waiting, since 671
was at that time the only exchange in that area served by one of the
new ESS switches), but as demand for it became more widespread, it
eventually became available on all phone exchanges as the older
equipment was phased out.
In Europe call waiting was also introduced in the 1970s with the
introduction of the first digital switching systems such as
theEricsson AXE , Alcat ... Ericsson AXE, AlcatelE10 and System 12. It
was also available on some Ericssoncrossbar exchanges, such as the
ARE11 which, while electromechanical, was computerised. Other digital
systems such as the UK's System Xalso supported the service. Switching
systems developed in the 1980s such as the German Siemens/ Bosch
EWSDalso had call waiting.
