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IP Intercom?

Posted: Mon Sep 22, 2008 1:36 pm
by Jim Barrett
Anyone out there ever use IP intercom?
I have a request for intercom from one door to several places in a large building. Cable runs in this building are time consuming and iffy enough that if I quote a dedicated wire I/C I'll have to examine almost every foot of path just to be sure I get no unpleasant surprises. If I can do this via IP then the computer guys are responsible for getting the cable to the computer.
Most of the I/C over IP systems I've seen are way overkill both in price and function.
Anybody got any ideas? :???:

Posted: Mon Sep 22, 2008 6:03 pm
by jwax
If your need for secure communications is not great, why not go with any of a variety of walkie-talkie style RF systems? Wireless intercoms. Or do you need to send data as well as voice?

Posted: Tue Sep 23, 2008 3:25 am
by Jim Barrett
Good question.
I guess I gotta say that in the long run I don't trust RF for permanant commercial or mission critical applications. I'm a communications tech by training & trade and probably spent half of my 30 year career doing two-way radio and RF system maint. & repair. RF interference, co-channel occupation, sunspots, electrical appliances and the FCC all seem to strike at seemingly random intervals. Most of these devices carry some variation of the infamous "this device may not cause any interference and must accept any interference" statement. My customers get cranky when I put something in and then 2 or 3 years later some amature radio operator (those guys are still out there, right?) or baby monitor starts causing their intercom to crackle.
Same reservations about power line modulation,wireless computer networks, etc.
I kind of believe wireless is a last resort when no wire is possible. I can control a shielded wire, I can't control the airwaves.
All that being said, I'm always willing to learn. Do you know of any particular device being used sucessfully?

Posted: Tue Sep 23, 2008 4:16 am
by Lenp
Is this an apartment like complex? If so consider a tenant call system that use the telephone lines. The dialer is at the door and it calls the tenant via handsfree phone. It even offers door release. You just need power and a telco line to the door


Posted: Tue Sep 23, 2008 5:11 am
by dr_when
What about the wireless line-carrier intercoms that are out there. I have used them throughout a home with no problem. There is a situation with multiple electrical circuits but I believe you can bridge breakers with caps to jump the circuits. (sorry...just saw you mentioned power line modulation...never mind)

Posted: Tue Sep 23, 2008 7:46 am
by Jim Barrett
Yeah, great minds must think alike. I was taking a shower at the gym this morning when that possibility occured to me. I'll have to look into their tel. system & see what will work. I wonder if you have to actually have a phone line or if hanging the I/C adapter on a line port will work.
Anybody know about these things? :grin:

Posted: Tue Sep 23, 2008 8:13 am
by Lenp
From my experience they are basically just an auto dialer and speakerphone. They dial a programmed number that is assigned to either a pushbutton or visitor entered numeric code. That way the actual number being dialed is not revealed. The tenant answers and talks to the door station. A code is entered on the tenant phone to release the mag lock at the door if entry is authorized.

A telco circuit that could dial another number via PSTN, PAX, PABX or what have you would work. Power+Telco=Success! (some may even be telco line powered)

I put one in several years ago for 'after-hours doctors' at a medical center. There are several available that physically connect to the tenant's telco line circuits to avoid an additional charge for the line to the door box. I think that scheme is opening a whole new can of worms!

Hope this helps,

Posted: Tue Sep 23, 2008 9:58 am
by Jim Barrett
Excellent, this is starting to take shape. Please tell me though why you are apprehensive about connecting to the pbx instead of a dedicated line. I can think of a few reasons...compatability with a given switch, I'd have to turn my wires over to the telephone guys for them to connect and program, once operational any problems likely become a joint operation between me and the customer's telephone people. You got any others?
Interestingly enough, as I was doing this I found out that the building (under renovation) has no telephone system right now, a new one has to be aquired. They will have to have several lines brought in anyway & I'll just tell them they have to have one for this thing.
Your suggestion certainly has the advantage of flexibility. There are three floors and one floor will be a tenant. Probably with their own phone system. What's the smallest those things come in re memory? 99 units I guess? 999?
I've already installed a networkable DVR & now have to quote this intercom and a magnetic lock on the front door.
Any insights you might have will be greatly appreciated. I'll start researching equipment but any steerage you can provide will be helpful

Posted: Wed Sep 24, 2008 10:18 am
by Lenp
Maybe my statement was a bit confusing so I'll try to make it clear.

The most basic unit dials a preprogrammed number to call the tenant. It uses a 'dedicated' line that supplies access to the PSTN. There's no reason it couldn't work on a PBX system since it is just a 'smart' phone. Quick install, simple wiring and no strings attached!

The second design, the one I have a bad feeling about does not use a 'dedicated' line. Each tenant's line goes through circuits in the door control. 100 tenants means 100 lines in, 100 lines out. Imagine wiring that if the outside plant wiring lands in wire closets on each floor!

When the door box is accessed it interrupts the normal telco circuit to the called tenant, rings the line, and then functions as an intercom. In my opinion that's way too much complexity, wire, work and way too many issues when the customer doesn't get a dial tone one day. All that just to avoid a basic line charge if it even applies.

As for the magnetic strike, there are many versions depending on the door hardware. That could be coordinated with the door supplier if these are new doors. I have cut jambs and fitted many locks but if the door jamb can be cut at the factory, you are way ahead. If you cut it, use the factory template, and if in any doubt, undercut. Mistakes are ugly, and costly to fix! If the door fitted with the mag lock is a critical access door the door should have a key system so it can stil be unlocked by someone in the event of power or mechanical failure. I did a card access system recently and after the installation, the customer had all the key locks removed and holes pluged. Yep, a window had to be broken to get in when the power was lost for an extended period of time.

Battery backup should be considered for both the call system and door lock since the telco system will probably be up during an outage. Most systems use 12-24 VDC so that is easy. Don't consider a UPS. The overhead is way more than the load so you'll be wasting valuable battery power.

If I can be of other help, feel free to post or PM.


Posted: Wed Sep 24, 2008 10:28 am
by Lenp
Duplicate post! Removed

Posted: Wed Sep 24, 2008 11:11 am
by Jim Barrett
OK, I gotcha. You're right about the line intercept concept. Way too complicated & peril fraught. A good example of "just because it can be done don't mean it should be done".
I do not like mag locks for primary security for the reasons you indicate. As a matter of fact this will be a school facility and I use a Locknetics device that has a built in PIR and fire alarm system connection. If anything goes wrong I want that door to pop open and people to be able to get out.
These doors have been so hacked and cut on that I won't even consider a standard strike.
I've only had two problems with this mag lock (it's really pricey by the way & has a long lead time from Locknetics). One, the doorframe was so chintzy that a 300+ lb guy grabbed the doors and started to jerk on them and he stressed the frame so hard the mag lock moved w/ the frame, the PIR saw the warm, moving floor and triggered. The other one was very small children who, bundled up for a Wisconsin winter, didn't generate enough IR signature for the PIR to detect. Same lock, same door, about 8 months apart.
Len, thanks for your help & advice. I'm a one man operation and it's always nice to bounce ideas off of another brain.

BTW, I suspect the autodialer function for residential is a dying thing . I know a lot of people who don't have a land line anymore and don't want their apartment ringing their cell phone.

Posted: Wed Sep 24, 2008 10:00 pm
by rshayes
One possibility is to have the telephone wiring done with Category 5 cable. This cable has four twisted pairs. A normal telephone jack would leave a maximum of three of these pairs, leaving the fourth one for other purposes. This will get you from a wiring cabinet to each of the rooms. A separate run woould have to be made to the doop. The wiring cabinet would be a convenient place t=for the intercom equipment as well, especially if it has 110 VAC already brought in for other purposes.

The extra cost for the Category 5 cable is probably far less than the labor cost of running separate lines for the intercom system.

Posted: Fri Sep 26, 2008 3:49 am
by Jim Barrett
Since this is an existing building they will be using the existing phone wiring so that's not much of a consideration.
OK, here's the scoop.
Viking door products has a single gang, stainless steel hands free door phone that can be connected to an analog phone port programmed for ring down to the customer specified extension(s) with distinctive ring.
Since there will be two facilities operating in the building I will mount two of them outside the door and run a cat5e cable back to the phone room, tagged so the phone guys know what to do.
I'm scrapping the mag lock on the door and will figure out how to use a standard strike but have not decided whether to use a phone line DTMF decoder or a wireless clicker to release the door. The elegant solution is DTMF but the program director in the building is enamored with clickers. I may just go ahead and do both. It looks like I can also program the video system so that when someone approaches or activates the intercom the video system will pop the door camera full screen for a few seconds.
This is gonna work folks.
The tech at Viking was most excellent.
Len, thanks for your help & input. Invaluable.
Alright, time to go out and pretend to make a living. :smile: