DSL & Home alarms

[joss]

I wanted to post this link for people with home alarm systems who are considering DSL. We had Sonic Fusion installed at my mother-in-law's house. She had a home alarm system and only phone service, no internet. We tried to do some research to make sure that the new service would play nice with the alarm.

During the pre-install days, our research turned up nothing helpful.We contacted Sonic and the alarm company to see if there would be problems. Sonic Tech Support felt that a DSL line filter would be sufficient to keep the alarm and the DSL separate. The alarm company answers were all over the map from: "it won't work", "it will work with a filter which we don't supply" to "install a second phone line dedicated to the alarm".

Well, post Fusion turnover, the alarm stopped working. When I located the place where the alarm came into the house, I found that I could not install a regular DSL filter. I thought the connector was an RJ45, because the connector was much larger than the RJ11 filter. But by searching for RJ45 and DSL, I found the above mentioned, below provided, link. Turns out the connector is RJ31.

To sonic Tech Support: does the information in this article make sense? We have not yet provided it to the alarm company because they don't have a way to contact them, except by phone. And then we get the answer that "DSL and alarms don't work on the same line."

It's a lot to absorb, but it is well written (IMO). So, without further preamble, here is the link I found.

http://members.cox.net/elangenb/alarmfilter.htm

[dane]

Seems like a reasonable solution. I don't have direct experience, but I think you are on the right track. Will you post here again and let us know how it turns out?

-Dane

[wa2ibm]

When I installed DSL at my mom's home, where she had an alarm system connected via an RJ-31, I inserted a whole-house DSL filter ahead of the RJ-31, passing the "phone" output to the RJ-31 and the DSL output to the DSL modem. All worked fine, including the alarm system, the ability to isolate the alarm with the RJ-31, and the alarms ability to seize the line when needed.

The RJ-31 connector has a pair of contacts that pass the incoming pair to the outgoing pair when the alarm 'plug' is removed. Since the alarm plug makes contact with the jacks pins prior to the contacts opening (make-before-break), the phone line isn't interrupted during insertion or removal.

My very first DSL service was IDSL. The installer used an RJ-31 for the modems jack, but shorted the output pair of the jack. During testing, one test involved shorting the pair. They just had me remove the jack from the RJ-31, which automatically shorted the line. Insert the plug and the line was open again. Remove the jack from the modem end and it tested with an open line.

[joss]

If a phone, instead of a DSL modem, was plugged into the DSL output, could that be used to bypass the line seizure? The article that I linked to notes that some people did that innocently: use a DSL that was split off before the phone entered the alarm system. This was into a home office and they then realized that they could split the line further and have a phone in the office off of that line. But since that phone is outside the Alarm Co's view, if it went off-hook, the alarm's seizure of the phone couldn't work.

I realize it would take a pretty quick, knowledgeable thief to be able to find the alarm input box, unplug the DSL modem, plug in an alternate phone and take it off hook; all before the alarm company was notified. But, still, they do that stuff all the time on "Leverage"....

[wa2ibm]

Yes, I suppose the alarm seizure could be bypassed in that scenario, but the filter I installed was inside the same closet as the alarm system, so they'd have to get past the initial alarm system itself in order to access that jack. And, if they got there, they could just unplug the alarm itself to accomplish the same thing.

As for inadvertently bypassing the alarm, that won't fly either because of the way I situated the equipment. But then, nothing is "Bullet Proof", only "Idiot Proof".

[joss]

So, we found a vendor who sells the filter in the article in my link. I installed the filter last week and was able to verify that the DSL connection works fine when the alarm is set.

But with or without the filter, when the alarm is set the phone service drops out. Once the alarm is turned off, the phone works again. Apparently the alarm company hardware seizes the phone line even if no alarm has been raised. This caused a problem when we inadvertently set off the alarm and the alarm company could not call to verify that it was not a true alarm.

We have updated the call list numbers with the alarm company to use cell phone numbers instead. But that seems more like a work-around than a solution.

[wa2ibm]

This sounds like a problem in the alarm system itself. The alarm system should only seize the line when it needs/wants to "phone home" such as an active alarm situation. I'd raise an 'alarm' with the alarm company over that.

[georgeharter]

I found the following information on the Broadband section of DSLReports. If I had had this info at the start of my Sonic.net Fusion service, or from Sonic Customer Support, or posted on Wiki Sonic, it would have saved me a lot of time in finding the source of the problem in streaming HD/HDX video. The DSL to my computers seemed fine when run thru the alarm box, but there was just enough signal loss or interference to create at problem when streaming video to my Blu-Ray player/TV. I have ADT alarm service with a GE Simon 3 panel common to thousands of California customers, so I know I'm not alone on this issue. A special alarm filter is widely available for alarm systems with a RJ31 jack (easy self-install) or better yet split off the DSL line as described below (more advanced users).

DSL and HOME ALARM SYSTEMS

If you have a home alarm system, do not put your alarm box in series with your incoming ADSL line!

Home security systems with dial-out alert capability are often installed IN-LINE.. in other words, your telco line comes in, goes into your alarm box, comes out and continues to your junction box. The alarm system, whether active, standby or unpowered, is not providing you with a clean connection.

Although you can get DSL Sync with this method, the Alarm system can attenuate (reduce) some of the high frequencies required for high speed, leaving you with poor performance or worse. Isolate your alarm system behind microfilters, or on the voice circuit behind a splitter, as you would any other phone in your house.