DSL Service and Your Security Equipment

Updated Information about DSL Service and Security Equipment

Note of Caution on Your DSL Modem Lines

If you have installed or intend to install DSL service, please contact DFT Security Customer Service to have your system evaluated and properly tested. Call 800-724-1057 and mention “DSL Filter”.

Improperly wired Digital Subscriber Line (DSL) service-high speed, simultaneous transmission of voice and data, including video, over telephone lines-can sometimes prevent an alarm system from transmitting alarm signals to the monitoring facility and/or interfere with the telephone line seizure feature of the alarm system. This is not due to equipment failure, but to improper placement of the DSL equipment in relation to the alarm panel.

There are two configurations of the installations that are present ly being made. These are "Split" and "Splitter-less" shown in the diagrams below.

Split Installations

An installation that the local telephone company may put in is a so-called Split Installation shown in Fig. 1. The telephone line comes through the network interface and immediately goes into a "Splitter". One line from the Splitter goes to all the extension telephones, FAX machines, low speed modems (up to 56k), answering machines, and any other equipment that is or was on your POTS (Plain Old Telephone System) line, without disturbing their wiring or connections. If an alarm system is on the premise and an RJ31X jack is used for the connection, all the above units are connected through the alarm panel's Extension telephone terminals. The second line from the Splitter goes directly to the DSL modem. This generally requires a separate wire to be run to the computer location. Telephones and/or other units that normally connect directly to a POTS line must NOT be connected onto the line to the DSL modem.

Splitter-less Installations

Since the Split type of installation requires a visit to the site by a telephone company serviceman, some new installations are being installed and proposed that can be done by the end user. No Splitter is needed in these installations. The DSL modem is sent to the subscriber along with a number of "micro filters". This type of installation is shown in the second diagram. The telephone line carrying the signals is not split and therefore the signal is present at all telephone jacks in the home. Therefore, plugging the DSL modem into an existing telephone jack is all that is needed to connect the PC. However, all other devices connected to telephone jacks MUST have a filter installed ahead of it. The provided filters have a RJ11 male and female section so the subscriber can simply unplug his telephone, plug in the filter, and then plug in the telephone again. If an alarm system is installed with a RJ31X jack, it is ahead of all the equipment.

Summary

In both types of installations described above, the alarm system will properly report to its central station. In the Split installations, the alarm panel never sees the DSL signal since the splitter filters it out before it ever reaches the panel. The DSL signal is undisturbed when either the panel seizes the telephone line or the telephone is in use by the subscriber.

In the Splitter-less installation described, the DSL signal is routed through the alarm panel, but when the panel seizes the line to make its call, it breaks the connection between the local DSL modem and the central office DSL equipment. Since the central office modem now does not see the signal from the subscriber modem, it stops sending out its signal and the telephone line now is quiet. Any reporting can now be done without the DSL signal present. The disadvantage to the subscriber is that his DSL connection is interrupted, and his computer must wait for the alarm report to be completed before the DSL connection is re-established. The DSL communication will restore with the modem within about 15 to 30 seconds after the line seize is released by the panel (training time for the modem). If the computer hardware and setup is proper, the actual DSL communication to the computer internet connection should also restore automatically. The best setting in Windows can be made via Settings; Control Panel; Internet Options; Connections; and selecting "Always dial my default connection". (More information will be available soon about how to avoid an interruption of internet service when the control panel is making a call.)

Although the frequency of the DSL signals are well above the audio band, certain characteristics of devices connected on the POTS line can cause extraneous signals to be generated and they will sound like a "white noise" level, i.e., like "sh-sh-sh-" on the telephone handset. This indicates that either the Splitter or Micro Filters have not been installed properly.

For more information on DSL Service and your alarm system please call 800-724-1057 and mention “DSL Filter”, a customer service representative will be more than happy to answer your questions or can direct you to a technician.

DFT Security is offering a special discounted price of $99.00 installed or $29.95 plus $5.00 shipping & handling for do-it-yourself installation (plus applicable taxes).