Alcatel Conference 1800 User Manual page 9

If you have a Broadband Line
If you connect your telephone to a line with a broadband connection, you will
need to insert a micro-filter between the telephone and the telephone line,
otherwise you may get interference between the telephone and the
broadband, which could cause problems.
In a fixed line with broadband, every telephone must have a micro-filter
connected, not just the one at the telephone point that your modem is
connected to. If you need more broadband micro-filters, contact your
broadband supplier.
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