4. Terminology
Line pick-up/seizure/off-hook – call start, line locked, busy.
Line hang-up/clear – call end, handset hang-up.
DTMF – dual tone multi-frequency signalling.
PSTN – public switched telephone network.
Outgoing call – Helios-telephone connection made, e.g. by a pressing a button.
Incoming call – telephone-Helios connection.
Programming mode – Helios programming mode accessible from by dialling into the
intercom only.
Code lock – mode for entering the password for switch 1 or 2 activation using a
numerical keypad.
Telephone mode – you can make a call, dial a number and hang up using the
numerical keypad.
DTMF transmission during call – for outgoing calls only, numbers are tone-dialled by
a numerical keypad button.
Button substitution – the numerical keypad can be used instead of a number pre-
stored under a button memory.
10
