Phone wiring question: RJ11 to RJ45

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I plan on installing a VOIP setup in my house.
The problem is that the phone wiring that enters the house is 8 conductor and is hardwired to the phone distribution center. So, I figure I can break into that incoming line and install a couple of cat5 8 conductor female plugs on the two severed ends and can use a cat5 patch cord to connect them if I ever want to go back to the teleco. But, that would only happen if I sell the house.
The question I have is: Can I plug in a normal rj11 modular plug (coming from the modem) into the female rj45 jack that I'll be installing upstream from the distribution center and expect those 4 conductors in the plug to be aligned with the appropriate conductors in the rj45 jack? The phone modem only has rj11 plugs.
BTW-I know I'll only be able to hook up one phone (an expandable wireless system) to this setup. I just want to make my setup easy to undo when I move.
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CraigT wrote:

RJ-45 is for network (ie ethernet), RJ-11 is for telephones. You are not going to hook your telephone to the network. You are going to hook your voip phone adapter or voip router to the network ( via an RJ-45 connector ) and then hook your telephone to the voip adapters' RJ-11 telephone port.
Eric
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Incorrect.
RJ-45 is for a dedicated single pair data circuit, and has nothing to do with ethernet.
The connectors themselves do not have any RJ designations until they are wired for a specific telephone application, as originally defined in 47 CFR 68.502.
The only exceptions might be jacks for alarm applications complying with RJ-31X or RJ-38X, which have shorting bars, making them difficult to use for other applications.
Ethernet and Token Ring do not have any RJ designation.
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Bob Vaughan wrote:

I don't see how the CFR can be authoritative in a non-telephone (e.g. ethernet) context.

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The RJxx designations are known as a Universal Service Ordering Code (USOC), and the wiring for specific telephone services was defined in 68.502, along with the associated USOC. The specification includes the type of jack/plug, wiring pattern, and signaling.
There is no USOC for ethernet or token ring.
The connectors are obviously used for multiple uses, only some of which have USOC's, and since the same connectors are used for multiple USOC's, the connectors themselves do not have a USOC until they are wired for a specific application.
The specification for the RJ45 USOC is for a keyed 8 position/8 contact modular jack/plug, wired for a single line, bridged tip/ring, wired on ping 4/5 of the jack/plug, with a programming resistor wired across pins 7/8 or the wall jack, with a value determined based on loop loss between the jack and the CO. This allows the connected equipment to set transmit levels to not exceed -12dBm at the CO.
For comparison, 10/100 ethernet uses an unkeyed 8p8c jack/plug, wired with one pair across ping 1/2, and the second across 3/6.
Note the lack of any cross-compatibility between RJ45 and 10/100 ethernet. If properly wired, using the proper connectors, and 2 pair cable, a cable wired for RJ-45 will not fit into an ethernet jack, nor will there be any electrical continuity on any of the wires used by ethernet.
The unkeyed 8p8c jack/plug are also used for RJ-31, RJ-38, RJ-61, and others, and the keyed 8p8c jack/plug is used for RJ-41, RJ-45, RJ-48, etc.
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Bob Vaughan wrote:

The confirmed number of people in the known universe who are offended at the LAN world's usurpation of the RJ-XX terminology now stands at 2. Me and Bob.
Keep up the good fight Bob. We shall overcome someday.
Now, about the word "modem"; but ... that's another fight for another day
--Reed (old modem jockey)
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Reed spake thus:

So, I'm curious: does a modem to you mean a big box with a cable coming out of it that has a cradle for a telephone receiver? I remember those from my school daze ...
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David Nebenzahl wrote:

I think you are describing an "acoustic coupler". Not the same as a modem. A modem used an A/C to "couple" it's signal to a standard telephone handset, without being hard-wired.
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The first modem I used was one of those "handset-coupled" things, operating at 300 baud.
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On Sun, 15 Oct 2006 19:42:08 -0700, David Nebenzahl

A modem is a mo and a dem in the same package, considering the fact that phone lines won't handle TTL levels.
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Bob Vaughan wrote:

How many angels can dance on the head of a pin? , in the day to day residential world this is the way its done RJ-11 for telephone and RJ-45 for ethernet. Eric
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x=1/0 :-)

I remember someone saying they ought to be called 6P4C and 8P8C (and RJ12 is 6P6C, what is 4P4C or 10P10C?). That describes the specific connectors, but sounds awkward.

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Actually, RJ-12 only uses 4 conductors, and can use a 6p4c, as can RJ-13, and RJ-14. RJ-25 uses 3 pairs, and requires a 6p6c.
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On Mon, 16 Oct 2006 20:39:48 +0000 (UTC), snipped-for-privacy@tantivy.tantivy.net (Bob Vaughan) wrote:

OK, I know the 4c or 6c is the max number of wires, but what does 6p mean, and what does Mark refer to wrt 4P and 10P?
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Position (maximum number of contact positions) Contact (actual number of positions available to be wired)
A 6p4c is a plug sized for a maximum of 6 wiring positions, but with only 4 of them having physical contacts. Frequently sized so that a maximum of 4 conductor cable will fit in the plug.
You normally only see the mismatched numbering in the 6 position plugs. You can get them as 6p2c, 6p4c, and 6p6c.
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Bob Vaughan wrote:

Everyone seems to have forgotten though that "RJ" defines a lot more than the number of positions and number of wires; it also defines the intended use of the plugs and receptacles and which pins are used for what. Specific examples: RJ-11, RJ31, etc. RJ-11 uses only the two center conductors for analog services, RJ-31 actually breaks a phone connection and allows one piece of equipment exclusive use of the telco pair, etc.. There are many RJ designations.
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On Wed, 18 Oct 2006 11:16:22 +0000 (UTC), snipped-for-privacy@tantivy.tantivy.net (Bob Vaughan) wrote:

I think I've seen a 4P2C once.
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On Sat, 14 Oct 2006 21:52:22 -0400, "CraigT"

They often do use cat5 for phone now, but the wires are probably all unused except for one pair (pins 4&5 on a RJ45 jack), as needed for phone. The extra ones could be useful in the future (maybe you'll want another phone line). You should not use the same cables for ethernet.

Or that VOIP company went out of business. That sort of thing does happen.

You can plug a RJ11 plug into a RJ45 jack. The shape of the plugs/jacks forces them to be centered. Pins 2&3 or a RJ11 plug (those normally used by a telephone) will connect to 4&5 or the RJ45 jack.
BTW, I was just in Lowe's and noticed they were only selling RJ12 connectors. A RJ12 is the same size as a RJ11, but has all 6 connections. RJ12 connectors can be used for phone with no problems, and fit into RJ45 jacks too. Pins 2-5 on a RJ12 match pins 1-4 on a RJ11. RJ12 does require a different crimping tool.

Never heard of these little things you plug in a jack and it makes two? Expandable cordless phones are still a good idea. I see some for sale that allow up to 10 handsets (I think Wal-Mart has one for about $100 with 3 handsets and you can add up to 7 more for $30 each).

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A houseful of cordless phones driven by VOIP.
Now *THAT'S* flaky. (Or likely to be.)
It could be worse: It could all be driven by satellite receiver.
Now that's REALLY flaky.
You'd be surprised at how many users soon reject the foibles of VOIP and return to an old-fashioned land line.
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JR

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wrote:

Chuckle. My employers are currently running VOIP phones over portable sat links at multiple sites- three guesses where- and we are currently dealing with a vendor for a micro-cell setup to run either private cell phones or long-distance cordless phones, hung off the same setup as the current PC-based VOIP phones.
Sound quality and reliability are less than optimum, but when you set up where there IS no local infrastructure, options are limited. Multiple hops halfway around the world, to call ten miles away, doesn't make for a great connection. No, you really don't wanna know how much it costs.
aem sends....
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