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VoIP and Home Security Systems Don't Get Along
coondoggie writes "Here is a story about consumer VoIP services that can cause your home security alarm system to malfunction or not work at all. There have been problems with customer phone systems in Canada who were using Primus but Vonage customers in the U.S have complained too. A number of sites have popped up offering suggestions to help deal with the problem."
If you''ve got VOIP, you've got an IP network.
Get an alarm system that uses your IP network rather than legacy POTS network.
Depend for emergency communication on a shared bandwidth communications link whose functioning depends on utility power availability coupled with some ISP's service plan, and maybe when the bad guys break in you won't get the call? Huh? You think? Or, to put it another way, there's no guarantee that The Phone Company's own landline will work perfectly either, but if I had to bet my home on it, I'd go with TPC over VoIP. In fact, personally, I've stuck with TPC landline because of E911, because my landline has always worked during NYC blackouts even when my cellular phone didn't, and because I have yet to see a VoIP service provider that would guarantee that if some guy in Afghanistan (or Milwaukee, for that matter) somehow manages to clone my SIP identity and proceeds to make N-billion dollars (well, amounts are relative to my savings account balance) worth of international phone calls, that they won't hold my feet to the fire if I refuse to pay the bill. But of course, you may see things differently.
>It's only too easy to cut a POTS line, or tie it up by dialing-in to it, which is exactly what any competent burglar will do.
In movies, and in some cities. Check with your local PD's crime prevention officer about trends in your area.
Random burglars do have the option of moving on to the house next door that doesn't have an alarm system at all, saving the precious seconds to locate and cut the line. Targeted attacks are rare and quite difficult to handle.
They know there's more important things to do like bust serious crimes.
If you're in the suburbs (30 cops in one town, one non-domestic violence crime in the last five years) that should read:
They know there's more important things to do, like generate ticket revenue.
Oh, I forgot one more thing:
Honestly, I could give a rat's ass if my alarm is top quality, I have it because I get a break on my home insurance, not because I feel safer when I go out.
There's nothing like the piece of mind that comes from knowing that if you forget to set your alarm and you get robbed your insurance company won't pay the claim...
...<snip>...Clocking is part of it, A/D and D/A another, but the compression algorithms used by the VoIP device itself are generally the main culprit of modem device failure. They are designed specifically to carry voice (hence the big V in VoIP), same as telephones and the POTS network were originally designed for, not modem tones. After all, why would someone want to send data via analog methods when a digital one is available, right? Oh yeh, faxes/creditcard machines/atms/alarms/firepanels/etc. There are solutions available. Unfortunately for the home consumer level products these probably are either not built into their systems, or they lack the ability to enable or configure them to mesh with the other end of the VoIP tunnel. On the higher end equipment, such as Cisco IAD style VoIP devices (routers with FXS cards basically), settings on the FXS ports can be tweaked to amplify the modem signal (boosting the gain and adding a DC offset voltage), altering filters and setting up special pass-throughs (fax T38 relay/mgcp modem passthrough), and special compression algorigthms can be applied to lines designated to be modem-type devices. Once this is done, however, that is all that line will be able to do, as voice itself is now not the intended data and is filtered out as a side-affect. The other end of the VoIP net, where/if it goes out to the POTS network (trunking gateways) must also understand these features so they can take the digitally packetized modem packets and re-assemble them correctly into a decent modem type noise for the POTs lines. For buisness grade, where the network is setup specifically for VoIP traffic, this type of traffic is expected, it is still sometimes difficult to get it working with 100% of the devices out there, and most modem devices will still only operate at a max around 33.6k. If you are using skyp/vonage/other consumer bring-your-own connection, good luck with that.
Tm
disclaimer: no, I dont work for Cisco, however I do work for a business-class VoIP provider that uses cisco equipment for its structured network, setup and QOS'd specifically for this type of stuff, including the end loop circuits (T1) and devices (IADs) at our customers' sites.
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