Additional telephony products on a BT Broadband enabled line

Published 18/05/2004 12:30   |    Updated 13/05/2008 11:09
Can I plug any telephony product into my BT Broadband enabled line?

BT Broadband is compatible with analogue telephony equipment developed to agreed standards. All equipment plugged into a BT Broadband line must be connected to a single socket microfilter. This includes satellite/digital TV boxes (including Sky boxes), smartboxes and alarm systems.


You should not connect your broadband modem/router through any internal equipment, such as a Ringing Equivalent Number (REN) booster or a smartbox - it should be connected directly to your telephone line through a double socket microfilter. If you are experiencing problems with any equipment, check that the microfilters are correctly fitted. Unplug the equipment to establish if is the only item affected. If you cannot resolve the problem, please contact your equipment supplier.


Make sure you don't have too many devices connected to one line. All phone lines only have a certain amount of power going through them, this power is measured in RENS (Ringer Equivalency Number). REN is the load a typical analog phone or other device imposes on the line when the phone rings.


Each line has on average 4 RENS available and every item of telephony equipment uses some of these RENS. Most telephony equipment unless otherwise stated uses 1 REN so the maximum amount of items you can have on one telephone line is 4. Any more than this may cause the DSL light to flash or go off on your modem/router. Depending on your type of line you may have less than 4 RENS available.


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