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Technical
Choosing a position
Your DF450 should be kept clear of dust, moisture, high
temperature and vibration and should not be exposed to direct
sunlight. Don’t install it close to radiators or air-conditioning
outlets or in excessively warm, humid or dusty places.
Warning
The apparatus is only designed to be operated in a normal office
or domestic environment where the relative humidity does not
exceed 60%. It should not be used in bathrooms or near water.
Connecting to the UK network
DF450 is tested and approved for connection to the UK network,
provided that it is used in accordance with the guidelines in this
booklet.
Approval number
BABT Certificate Number/Approval Number for the DF450
503727 APPROVED for connection to telecommunication
systems specified in the instructions for use subject to conditions
set out in them. CE compliant to 89/336/CEE (EMC Directive)
Approval for use
This apparatus has been approved for use with the following
facilities:
Storage of telephone numbers for retrieval by a predetermined
code. (If problems occur, verify stored number).
Automatic call initiation.
Use on a PBX which returns secondary proceed indication.
Operation in the presence or absence of initial or secondary
proceed indication.
Automatic dialling facilities.
Automatic storage of last number dialled.
Automatic repeat attempt facilities.
Auto clear from the originating end.
Series connection facility.
Call progress monitor.
You may connect it:
• to direct exchange lines:
• to extensions with new plug and socket arrangements provided
with these direct exchange lines;
• to compatible switchboards.
You may NOT connect it:
• to shared service (party) lines.
The connection to the telecommunication system must be
unplugged before the earth is disconnected. The connection to
the telecommunication system must not be hardwired.
This apparatus may be used on telecommunications systems
employing loop disconnect or MF signalling.
Any other usage will invalidate the approval of the apparatus if, as
a result, it then ceases to conform to the standards against which
approval was granted.
How many phones you can have
Your exchange line provides only a small current to make your
telephone ring. Although you may have any number of sockets it
is important to limit the number of telephones and other items of
apparatus connected to the line by these sockets. This ensures
that each telephone will receive enough current to ring.
Every telephone or item of apparatus has a Ringer Equivalence
Number (REN)
In most cases a standard line should provide enough current for
two or more telephones or items of apparatus, if the RENs add up
to no more than 4.
DF450 has a REN of 3. Any telephone provided by BT may be
assumed to have a REN of 1 unless otherwise stated on the base.
Even where the number of telephones has been limited, there is
no guarantee that the different types of telephone on the same
line will ring.
Technical information