How do phone lines connect

[RoamDog]

OK. I just got a patch panel to terminate all my data drops. My electrician comes out next week to wire it up. However, I also had some cat5e run for phone jacks. And then I started thinking, "how do these phone lines hook into my phone service"? Can somebody explain what equipment is involved and how the wires all connect? I know that this should be easy to see/understand, but I am not getting it?

 

[spidey07]

It's not easy to understand actually...

Here's a start...

http://en.wikipedia.org/wiki/Pstn

 

[Viperoni]

I just rewired my house using cat5 as phone wire, and it definetely improved my phone quality. I also used a DSL filter/splitter, which seperates voice from DSL signals, and that helped a lot too.

The cat5 is treated as regular phone cord, just with different colour codes.

 

[RoamDog]

But how does all the wire from all the phone jacks scattered throughout the house connect to the phone company? Seems like there has to be a piece of equipment in there somewhere that functions like my cable modem/router (but for phone service)? And will it be a problem if some of my wire is the old style and some is cat5e?

Originally posted by: Viperoni
I just rewired my house using cat5 as phone wire, and it definetely improved my phone quality. I also used a DSL filter/splitter, which seperates voice from DSL signals, and that helped a lot too.

The cat5 is treated as regular phone cord, just with different colour codes.

 

[Viperoni]

The telephone wiring gets split at punchdown blocks such as these:
http://www.hometech.com/techwire/head.html#LE-47690110

Are you going to be running DSL?

 

[nweaver]

often, older homes (even some newer) are wired serially, so that you go from the telco block outside on the house, to room 1, to room 2, to room 3, etc.

Not always that way, but usually. I am about to run a punchdown block and rewire all the rooms in my house, but my home makes that painfull, so I have been putting that off.

 

[Ernie99]

The place you want to start is the demarcation point between the phone company wiring and your in-home wiring. The demarc is where the telco terminates its end of the wiring, and it could be one of many things, but essentially you have several pairs of wires that come off the pole to your demarc.

Each pair denotes a single "line" of service. Typically, one pair is terminated on the telco equipment for the single phone line you have. Your in-home wiring patches into this connection (normally set screws with the bare wire twisted around it). One pair of wires is all you need for a single phone line. With CAT 5e wiring, typically the White/Blue, Blue pair is used. With standard telephone cable, the Red/Green pair is used. CAT 5 is overkill for regular voice communication such as this, but it can also be used for other things like data transmission so it makes sense to run it in the walls of your home.

There is no "technology" probably until your wire travels back to the telco Central Office (CO). Until then, your line goes through in-line amplifiers to just keep the signal level up.

 

[RebateMonger]

As noted, for POTS (analog) phone lines, there's no electronics involved in splitting up the signal. You simply hook a bunch of wires together and run two leads to every phone in the home. (Two leads for each phone line, that is).

In a typical house, they've either run a single cable all the way around the house (putting all the phones in parallel on the wires), or have run "home runs", where a separate cable goes to each phone. Or, maybe, some combination of these two methods.

 

[cmetz]

RoamDog, traditional phone jacks are one big parallel circuit. A cable goes from your NID to jack A, which goes to jack B, etc. Wire one from NID to A is connected to pin X in the RJ11 AND to wire one on the cable to jack B, where it repeats. Visualize a ladder running horizontally, where the bars represent jack positions. A phone that's on hook is at high impedance, so it doesn't complete the circuit there, but a phone that's off hook is at low impedance and that's where the top and bottom rail (tip and ring) are connected.

If you use network style home-run wiring for your jacks rather than the traditional chaining, it's just like having a really short chain near your panel and really long cables going from there to the phones. So you'll need a special panel, or you'll need to make one yourself, that simply connects all the pin 1s together, and then separately connects all the pin 2s together, etc.

If this all still seems too complicated, I believe that Lowes and Home Depot both carry a little panel that does all the chaining internally, so you just connect cables from your patch panel (and from your NID) to this little daisy-chain panel.

I admit that this is a bit hard to explain in a text-only format.

 

[Viperoni]

Here's basically how the signal should run:

Demarc box -> punchdown block -> runs of wires to each phone outlet it house

As mentioned, the demarc box is where your local telephone company connects its lines to your house. It alsp provides lightning surge protection. Then from the demarc you have a line going to a punchdown block. Think of a punchdown block as an power bar: it takes the pair of wires for each line, and splits it so that many more pairs of wires can connect. Then from the punchdown block, you have all of your wire runs to each phone outlet.

What I did, because I'm running DSL and I wanted a higher quality signal than could be achieved with the "microfitlers" that are plugged inline with each phone, is I bought a whole house DSL "filter/splitter".
It gets wired between the demarc and punchdown block, typically right beside the punchdown block. It has 1 input for a single phone line, and provide 2 outputs, one for DSL which goes directly to the DSL modem only, and another voice only output which goes to the punchdown. That prevents your regular house phones from getting high frequency DSL frequencies (no need for microfilters), and filters low frequencies from the DSL modem. It made a PROFOUND difference in my DSL modem's signal quality stats. I can now connect at a higher speed with greater stablility.
HIGHLY recommend that you run this setup if you will be running DSL.
The DSL filter/splitter is only ~$30, and worth every penny.