Determining if phone line is down

[Ira]

Are there any "retail" devices that can detect whether or not a phone line is up/down, that can also somehow be hooked to an Elk M1G zone so that the M1G can take an action? This would not be the same phone line that is connected to the M1G. Also, the only "state" I'm interested in is whether or not the phone live is up. On hook, ringing, in use, etc. would all be considered "up".

Thanks,
Ira

 

[WayneW]

there is no retail device that I recall that would have a relay output for use on a zone input.

http://www.securitystoreusa.com/Eagle+Secu...E+-p/547536.htm

 

[PaulD]

A phone line has a voltage when it it live. Can you monitor that voltage and detect when it goes to zero?

 

[Quixote_1]

A phone line has a voltage when it it live. Can you monitor that voltage and detect when it goes to zero?

Shouldn't a simple transistor be able to do that?

 

[Ira]

there is no retail device that I recall that would have a relay output for use on a zone input.

http://www.securitystoreusa.com/Eagle+Secu...E+-p/547536.htm

That device looks interesting, but I wish the "delay" could be shorter (I seldom have phone outages).

What I would like to do is use a POTS line that is dedicated to DSL as my primary M1G line and the HAI C3 cellular device as the backup. That way, it wouldn't interfere with any calls on my "regular" phone lines when it dials out. Unfortunately, it looks like that defeats one of the HAI C3 benefits of allowing the CS to call back in thru the cellular line to get to my phones since they won't be on the same POTS line that is connected to the C3.

So, I was thinking that if I can find a device that will detect my phones' POTS line losing service (not just physcially cut) and drive an M1G zone when it happens, I could use an M1G relay (actually two relays) to switch my phones to the POTS line connected to the C3. Then, when the CS called in via the C3 cellular line, my phones would ring.

Is it just me, or is the above very confusing? :huh:

Thanks,
Ira

 

[Ira]

I found this when I googled "phone line voltages"...

When the telephone is NOT in use (on hook) the voltage across the two wires (tip and ring) is about 48 volts D.C.

When the telephone IS in use (off hook) the voltage across the tip and ring wires drops to about 6 volts D.C.

When a ringing signal is being sent there is an A.C. voltage "superimposed" on top of the normal D.C. voltage. This "ringing voltage" is nominally about 90 volts at 20 Hertz (cycles) but could be as high as 130 volts and at different frequencies.

I guess all the different voltages may preclude a simple solution. Plus, I'm an COTS electronics kinda guy anyway. The device WayneW posted would be exactly what I want if it had a shorter delay time, like maybe five seconds, instead of sixty seconds.

Ira

 

[BraveSirRobbin]

I'm probably not seeing the entire picture here, but can't the Elk detect a problem when voltage is lost on the phone line? Couldn't you develop a rule to trigger an output based on this trouble notification?

 

[midon]

there is no retail device that I recall that would have a relay output for use on a zone input.

http://www.securitystoreusa.com/Eagle+Secu...E+-p/547536.htm

What I would like to do is use a POTS line that is dedicated to DSL as my primary M1G line and the HAI C3 cellular device as the backup.

This device *might* do what you're looking for (I think! - hard to tell): Suttle Phone Switch

 

[Sandpiper]

I'm probably not seeing the entire picture here, but can't the Elk detect a problem when voltage is lost on the phone line? Couldn't you develop a rule to trigger an output based on this trouble notification?

There is a rule available for this. "Whenever phone line trouble" occurs. I suspect that "trouble" occurs when the M1 detects the phone voltage to be less than 3 or so volts. Many alarm panels can detect phone line trouble.

 

[WayneW]

I'm probably not seeing the entire picture here, but can't the Elk detect a problem when voltage is lost on the phone line?

There is a rule available for this. "Whenever phone line trouble" occurs.

from, the OP:

This would not be the same phone line that is connected to the M1G.

 

[Ira]

The issue is two-fold. The first, as WayneW posted, is that the phone line I want the CS to call back on is not used by the M1G. Although, if one line is down it's likely that both are.

The second/real issue is that I'm assuming that if I use the HAI C3, it causes the M1G to never see a phone line outage. It detects the outage first, then switches over to its cellular capability. I haven't read anywhere that the M1G will see the switchover.

Here's the scenario...all phones are on POTS line 555-1111. POTS line 555-2222 is used for DSL (no phones) and plugs into the HAI C3. The C3's cellular number is 555-3333. So if the M1G needs to report something to the CS, it will go out on 555-2222 if the POTS line is available, or 555-3333 if the POTS line is down. CS primary callback number is 555-1111, which normally has all the phones on it. The CS secondary callback number is 555-3333. Someone disconnects all phone lines at demarc. Because of the HAI C3, the M1G does not detect this. However, the "phone line down detection device" does see it, so its relay causes a M1G zone open event. A rule in the M1G causes a DPDT relay to switch, which results in all phones now being on 555-3333 (cellular number via the C3). The rule also might go ahead and signal the CS that the "primary" M1G phone line is down (if that is usually done). If a subsequent break-in is detected, the M1G will report over the cellular number. If the CS calls the primary number 555-1111, it will get no response because the line is disconnected at the demarc. The CS calls the secondary number 555-3333 which gets thru because it is the cellular number. All the phones ring because the relay switched the phones to the wire coming out of the C3. Does all of this work?

Too bad the HAI C3 doesn't have a dry contact that signifies that the POTS line is down.

Thanks,
Ira

 

[felixrosbergen]

ELK makes the separate phone line detection device..which has a relay output...you should be able to put that on a line other than the one the ELK uses to call the CS. Actually i don't see why you cannot have multiple of these and monitor multiple lines that way.

If the phone is dead it takes my ELK a while to give a 'phone fault' or something like that. I guess it only checks periodically or something.

 

[fcwilt]

Why not just use the voice line for the ELK?

 

[Ira]

ELK makes the separate phone line detection device..which has a relay output...you should be able to put that on a line other than the one the ELK uses to call the CS. Actually i don't see why you cannot have multiple of these and monitor multiple lines that way.

If the phone is dead it takes my ELK a while to give a 'phone fault' or something like that. I guess it only checks periodically or something.

I think you are talking about the Elk-980 phone line fault monitor. I came across that doing some searches. Unfortunately, it has been discontinued.

I found a device from Telular and another from Ademco on eBay that look like they do the same thing. Both have delays of 30 seconds, so I guess that's the best I can find. I've ordered one of each and will update this thread with what I find out once I've had time to play around with them.

Ira

 

[Ira]

Why not just use the voice line for the ELK?

If you mean use my regular POTS voice line for the primary line for the Elk...its because I don't want voice calls terminated by the Elk when it decides to phone out an alert. If I set up the rules such that it only phoned out when it was in "away" mode, that wouldn't be a problem. However, there will be some things that I want it to phone out even if there is someone home and the system is not armed or is armed "stay".

Ira