Alarm Filters with ADSL Broadband

Views 83 Likes Comments Comment
Like if this Guide is helpful

The Problem

Alarm systems present a particular problem.
For a start, the alarm panel must have an ADSL filter, but more of this later.
The general method of installation in Australia is what is called “Mode 3”.
With this, when the alarm is activated, or the system makes a back to base check call, all telephone devices, including the ADSL, are disconnected. This is so that the security of the system is not compromised.
Most ISPs recommend installing a Central filter if you have an alarm system.
This is however not a satisfactory method. The main problem being that one of two things can happen.
For the ADSL not to be disconnected when the alarm is activated, or the system makes a back to base check call, it is necessary to connect the incoming ADSL line directly to the Modem, thus the security of the alarm system is compromised since any fault, or even an off hook telephone on this line will prevent the alarm system from dialing out.

Thus a method must be devised whereby, when the alarm is activated, or the alarm system makes a base check call, the ADSL is not interrupted, but interference, or a fault, with the line to the modem  does not prevent the alarm from dialling out.

The Solution

If the ADSL line is connected after the alarm panel, in the event of the alarm activatation, or the system making a back to base check call, the ADSL will be disconnected.

There is one way to overcome this problem, and it is an international solution which is not generally installed in Australia, since most alarm systems use the old Telecom 611 plug for Mode3 installation.

Instead of using the old 611 socket, the international standard RJ31X socket should be used. This simply replaces the 611 and still conforms to Telstra specifications, in that it is an 8 pin 8 Connector (8P8C) and accepts the RJ45 plug for the alarm panel connection.  

The RJ31x socket will "normal through" the telephone line connections to the in house telephone circuits if the plug to the Alarm Panel is removed for service etc.

In the above picture, the normal telephone line from the exchange is installed on the left or right hand side and the normal in-house telephone cabling is installed on the opposite side. Connection is by screw terminals.

The cable plugs into the socket and the spade terminals are connected to the appropriate terminals on the Alarm Panel.

You can see the RJ31X socket connections here.

medicash2.c om/RJ31/RJ31XX.htm (Remove the space in com and put www in front)

Installation of the RJ31X socket in no way affects the normal operation of the alarm panel system, or the telephones, of your existing set-up.

The ADSL Alarm Filter

There is only one specialized ADSL Alarm Filter made. This is the Z-A431PJ31X-A made by Excelsus. This alarm filter is simply installed by unplugging the plug which goes into the  RJ31X socket, plugging in the filter to this and plugging the disconnected cable into the socket on the filter.

Here is some info on the alarm Filter:

medicash2.c om/RJ31/AlarmFilter.wmv (Remove the space in com and put www in front)


After the Alarm filter is installed it is up to you as to whether you install a Central Filter, or in-line filters and Splitters. Remember that all telephone devices must be fitted with a filter.

Either way, the alarm system security is not compromised, the ADSL to your modem is not disconnected in the event of an alarm or back-to base check, the alarm panel is filtered and it conforms to international specifications.

Important Note

If a Central filter is installed, it must be installed after the RJ31X socket. That is the in-house wiring side, not the exchange side. If it installed before the RJ31X socket the same situation as explained above can occur, the alarm is compromised because the alarm panel may be disabled via the modem line.




Have something to share, create your own Guide... Write a Guide
Explore more Guides