2N Lift emergency phone 2N SingleTalk - Manual, 1514 v6.3.0 - Manual (Page 61)

Function Description 4.1
60
Section 3.6).
Caution
 The quality of PSTN connection does not always allow for a reliable
recognition of all the situations mentioned above. Any excessive noise in
the lift car can have a negative impact too, slowing down, yet never
discontinuing, automatic dialing (the busy tone is not detected). It holds
true in general that the DTMF is the most reliable way of signaling and so
is preferred for confirmation. However, the connection is established (yet
for a shorter period of time) even in extreme cases, e.g. when the ST is
unable to recognize the DTMF).
Automatic Repeated Multiple Numbers Dialing without
Confirmation
This mode can be used wherever no trained staff for automatic dialing with
confirmation is available. The called person need not press any button. The two modes
have a common set of numbers, count of cycles, identical responses to the busy tone,
and so on.
The difference is that the non-confirmation mode detects the ringing tone and, if this
tone is terminated before the pre-defined count of rings is reached, it assumes that
the called party has answered and the connection has been established successfully.
Warning
 If you select this mode, make sure that it works reliably. Remember that
different countries and networks may use different dial tones and your dial
tone may not be recognised correctly.
Note
 In this mode, the ST does not repeat the “Wait please...“ message (or any
relevant user-recorded message) after the dialing end because this would
make it impossible to recognize the ringing tone reliably. The message is
reproduced once shortly after the called party answers. The ST cannot be
controlled using buttons
to
Evaluation of Situations during Speakerphone Automatic
Dialing without Confirmation
Situation
ST Activity
Silence or busy tone is heard upon
seizure
This has no influence on the operation; the ST
executes dialing with any line status and only then
evaluates the situation
Busy tone
The ST hangs up in approximately 2 seconds and
dials the following number