Voltage drop
The voltage drop introduced by the apparatus between the PSTN and the associated telephone/answering machine is 0.4 Volts at 40mA dc.
The introduction of this voltage drop may occasionally cause difficulties in making calls from the associated telephone or problems in telephone conversations being experienced by both parties to the call.
While operation may be possible initially, changes to or modernisation of the network taking place in the normal course of events may result in the apparatus being connected to a network service with which it is not designed to be compatible. Failure of the apparatus to work under these circumstances may not be the responsibility of the network operator.
In the unlikely event of any such problems occurring, the user should contact the supplier or maintainer of the apparatus.
Difficulty may be experienced when making calls from other apparatus. Such difficulties may include:
•difficulties in making a call;
•problems in telephone conversation being experienced by both parties to the call.
Note - The definition of a RBS (Relevant Branch System) from PSTN lines is given in BS6789 section 6.1 (1986) clause 2.4
Connecting to switchboards
Your DF450 is approved only for use with a compatible switchboard including those which do not provide secondary proceed indication.
If you do have a compatible switchboard, it cannot be guaranteed that the DF450 will operate correctly under all possible conditions of connection.
If you have any difficulties, contact BT on Freefone 0800 800 152.
Technical
Safety warning
Interconnection circuits should be such that the equipment continues to comply with the requirements of 4.2 of EN 41003 for TNV circuits and 2.3 of EN 60950 for SELV circuits, after making connections between circuits.
Interconnection directly, or by way of other apparatus, of ports marked Safety Warning. See instructions for use. Ports marked or not so marked may produce hazardous conditions on the network. Advice should be obtained from a competent engineer before such a connection is made.
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