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This topic discusses various wiring schemes for residential telephone wiring.

Note: The information presented here is for illustrative purposes only. Use it at your own risk. Read and understand the Disclaimer and Terms and Conditions of Use pages before proceeding.

In the information to follow components that I believe meet ANSI/TIA/EIA-570-B standards are listed in highlighted text. Unhighlighted components may or may not meet the standard. The standards and equipment shown here may not be applicable, available, or legal in your area.

Glossary

Term	Description
6P4C	Six Position Four Conductor Modular Connector
6P6C	Six Position Six Conductor Modular Connector
8P8C	Eight Position Eight Conductor Modular Connector
IDC	Insulation Displacement Connector
110 IDC	110 Style Insulation Displacement Connector
L1	Telephone Line Number 1
L2	Telephone Line Number 2
L3	Telephone Line Number 3
L4	Telephone Line Number 4

Topology

I chose a Star topology for my home. With a Star topology every jack in the home connects to a single distribution point using its own, dedicated cable. Older wiring I've seen used either Ring, Bus, or Hybrid topologies. A good explanation of all these topologies can be found at Phone-man's Home Phone Wiring Advice Page - Routing of Your Phone Cable.

Leviton's Installation Manual for Residential Structured Wiring - Version 3.0 says "TIA/EIA-570-B calls for star topology in residential and light commercial cabling systems."

Equipment and Connections

This section shows some of the devices, wires, and connectors used in home telephone wiring. It starts where the telephone service enters the home and follows the signal straight through to individual telephones at the end of the line.

Demarcation Points

Demarcation points are where the phone company's wiring interfaces with the homeowner's wiring. They can be implemented with the following equipment.

Input	Telephone Company Wires
Device	Network Interface Device(s) (NID)	Protector Block + Surface Mount Jack Block	Protector Block
Output	6P Jack	6P Jack	Screw Terminals

One or more of these devices may be installed depending on how many phone lines enter the home.

Patch Cables

Patch cables connect the demarcation point(s) to the distribution device.

End 1	6P plugs for demarcation devices with 6P jack outputs or unterminated cable for demarcation devices with screw terminal outputs
Cable	Category 3 / 5e / 6 Cable	Quad Wire	Flat Phone Cable
End 2	Unterminated

Quad and flat cable are more susceptible to crosstalk and induced electrical noise than Category 3/5e/6 cable. For short patch cables that are not near any electromagnetic fields this may not be a problem.

Distribution Devices

Distribution devices take signals from demarcation points and route them to the individual cables that feed each telephone jack in the home. These are some possible configurations.

Input	110 IDC	110 IDC	IDC	110 IDC	6P Plug
Device	Patch Panel	Patch Panel	Unbridged Punch Block - e.g. 66 Block, 110 Block, BIX Block - installer must bridge input signals and cross-connect them to outputs	Bridged Telephone Punch Block - e.g. Leviton LE-47603-110	Multi-outlet Adaptor - patch cable is built-in
Output	8P8C T568A Jack	8P8C T568A Jack	110 IDC	110 IDC	6P Jack
Cable	T568A patch cable with 8P8C plugs
Input	8P8C T568A Jack
Device	Patch Panel Jack
Output	110 IDC

This is one of the more complicated parts of a home phone network because of the many different ways it can be implemented.

In older days the incoming phone line would connect to screw terminals on a protector block and all the wires for all the phone outlets in the home would connect to the same screw terminals. These days there are more reliable options.

A multi-outlet adaptor is a cheap, simple solution when a single phone line feeds only a few outlets. For two or more phone lines or more than 5 outlets other devices may provide a better solution.

Bridged punch blocks can support more outlets than a multi-outlet adaptor. They require a special punch down tool to make connections however.

Unbridged punch blocks provide more flexibility than bridged punch blocks since they can be used for patching both voice and data jacks, but they require more connections than bridged punch blocks. This is because unbridged punch blocks only provide a mechanism for a 1:1 connection between two wires. In a telephone circuit each incoming wire must be connected to not just one, but many outlet wires, i.e. a 1:M connection. To achieve 1:M connections with unbridged punch blocks installers must manually bridge the inputs. See Phone Man - Wiring Block Techniques and Tips for more information. Unbridged punch blocks also require a punch down tool to make connections.

Patch panels provide even more flexibility than unbridged punch blocks becuase signals can be rerouted by simply reconnecting a few patch cables, but they can be physically bigger and more expensive than the other solutions mentioned so far. Some patch panels will provide bridged jacks for the incoming voice signals. Others will require the installer to manually bridge the signals.

Station Wire

Station wire is the cabling that connects the distribution device to all the voice and/or data outlet jacks in the home.

Distribution End	unterminated cable connects to distribution devices with IDC outputs or 8P8C T568A plugs connect to distribution devices with 8P8C T568A jack outputs or 6P plugs connect to distribution devices with 6P jack outputs
Cable	Combination Cable - contains various combinations of: Category 5e 4-Pair, RG6, and Fiber Optic cables	Category 3 / 5e / 6 4-Pair Cable	Quad Wire	Flat Phone Cable - for short, exposed runs only
Outlet End	unterminated
Max. Phone Lines	4 lines per 4-pair cable	4 lines	1 line	1 line

Safety/electrical/building codes may call for "riser rated" cable when cables run between floors and "plenum rated" cable when wiring runs through spaces used by HVAC systems.

Quad and flat cable are more susceptible to crosstalk and induced electrical noise than Category 3/5e/6 cable.

Even though Quad and Flat cable have four conductors, I would not use more than two of the conductors (i.e. use only one phone line per cable). Sending two phone lines down Quad or Flat cable can produce crosstalk between the lines (something I learned the hard way after my first rewiring project).

See Cable for some pictures and more information on cable used for station wiring.

Outlets

Outlet jacks are typically located in wall plates or surface mount blocks. They have inputs and outputs like these.

Input	110 IDC	110 IDC	110 IDC	Screw Terminals
Output	8P8C Jack	6P6C Jack	6P4C Jack	6P4C Jack
Max. Phone Lines	4 lines	3 lines	2 lines	2 lines

One of the assignment schemes below can be used to connect station wire to the jack.

Jack	Assignment	Notes
8P8C	T568A	- up to four lines available
6P4C	L1	- aka RJ11
	L2
	L3
	L4
	L1+L2	- aka RJ14
	L3+L4
6P6C	L1+L2+L3	- aka RJ25 - three line equipment is rarer than one and two line equipment

Telephones

There are a number of ways to connect telephones to outlets. The solution used depends on the type of jack, the type of phone, and which phone lines the phone needs access to. Here are some examples.

Single Line Phones to 6 Position Jacks

Jack Size	6P4C								6P6C
Jack Configuration	L1	L2	L3	L4	L1+L2		L3+L4		L1+L2+L3
Splitter						L1+L2 to L2		L1+L2 to L2		L1+L2+L3 to L2	L1+L2+L3 to L3
Cables	Telephone Line Cable
Device	Single Line Telephone
Available Phone Lines	L1	L2	L3	L4	L1	L2	L3	L4	L1	L2	L3

Two Line Phones to 6 Position Jacks

Jack Size	6P4C						6P6C
Jack Configuration	L1	L2	L3	L4	L1+L2	L3+L4	L1+L2+L3
Cables	Telephone Line Cable
Device	Two Line Telephone
Available Phone Lines	L1 - Primary	L2 - Primary	L3 - Primary	L4 - Primary	L1 - Primary L2 - Secondary	L3 - Primary L4 - Secondary	L1 - Primary L2 - Secondary

One and Two Line Phones to 8 Position Jacks

Jack Size	8P8C
Jack Configuration	T568A
Splitter		L1+L2+L3+L4 to L2+L1	L1+L2+L3+L4 to L3+L4	L1+L2+L3+L4 to L4+L3		L1+L2+L3+L4 to L3+L4
Cables	Telephone Line Cable
Device	Single Line Telephone				Two Line Telephone
Available Phone Lines	L1	L2	L3	L4	L1 - Primary L2 - Secondary	L3 - Primary L4 - Secondary

Four Line Phones

Jack Size	6P4C		8P8C
Jack Configuration	L1+L2	L3+L4	T568A
Splitter			L1+L2+L3+L4 to L1+L2 and L3+L4
Cables	2 Separate Telephone Line Cables per Phone
Device	Four Line Telephone
Available Phone Lines	L1 L2 L3 L4