2N Door intercom 2N Helios - Manual, 1322 v3.0 - Manual (Page 61)

Section for Advanced Users 4.2
61
If the ringing tone stops before the predefined count of rings is achieved and the call
is thus very short (e.g. 2 seconds), it is not clear whether the call should be regarded
as successful. Therefore, a new type of automatic dialling has been added - type 4.
The difference is as follows:
 Type 3 regards such a call as successful only if the door is opened.
 Type 4 regards all such calls as successful.
Automatic Multiple Number Dialling with Confirmation
This mode is used where maximum connection reliability is required – for emergency
calls. The called line (the supervisory control centre, e.g.) must be operated by a well-
trained person to confirm connection. The DTMF is used as the most reliable criteria
for successful connection. The called line must press
on its telephone. If the called
number is busy or remains unanswered until the preset timeout or in other cases (see
the table), 2N® Helios dials the next number in the sequence.
Evaluation of Situations in Audible Automatic Dialling with Confirmation
Situation
2N® Helios Action
Busy tone
Hangs up in approximately 2 seconds and dials the
next number.
Call or silence
Waits for the preset timeout (log-in time), then hangs
up and dials the next number.
Ringing tone
Waits for the preset count of rings, then hangs up and
dials the next number.
Continuous tone (at the PBX, e.g.)
Hangs up in approximately 2 seconds and dials the
next number.
DTMF char or
Immediately hangs up and dials the next number.
DTMF char
Confirms reception (2 beeps) and the call continue for
the preset time at most (maximum call duration).
These digits are interpreted as control characters -
refer to the DTMF Control subsection.
Note
 It is sometimes difficult to recognise the above-described situations
reliably due to a poor quality of the PSTN connection. Excessive noise in
the surroundings may also have a negative impact. However, this may
only decelerate automatic dialling (the busy tone may not be recognised,
e.g.). Even if 2N® Helios cannot identify the DTMF, the connection is
established (yet for a shorter time).