Basic Wiring

The link below is about as simple as it gets. It shows the new and old color codes and the pairs associated with them.

How to Wire a Phone Jack (Voice or Telephone RJ-11 thru RJ-14)

Wiring is now done in a star configuration which means that all of the phone jacks should terminate at one location.

The link does not cover the even newer use of CAT-5 or better cables and an 8 conductor RJ45 type of wiring system rather than the more standard 6 conductor system.

Telephone wiring in a modern home can get quite complex. The term coined for this is "structured wiring".


Two-Line systems
The jacks will have line 1 and line 2 terminated for use with a dual line telephone device. Instead of re-wiring the jack to use a single line device, it's best to purchase an adapter which has 3 jacks. One for line 1, one for line 2 and one for line 1 + Line 2. The first two jacks will place the identified line on pair #1.

DSL

DSL - What they don't tell you
When the DSL modem is off and if there are no filters anywhere, all of the jacks are essentially a normal phone jack. If the modem is turned on, the line will have a slight hiss to it. The filters remove that hiss. It lets the phone see the voice spectrum and also passes a DC voltage to the phone.


DSL - Splitters vs. Filters
DSL standards typically state that a maximum of 5 filters are to be used on a line. If more are required, one must use a splitter. Splitters can be placed in the NID or in a separate box.

DSL - Modem wiring
Best practices when wiring the modem to reserve the last pair for DSL. For the best performance, it's best to limit the distance from the splitter to the modem and use cat5E or better cable. Wireless, routers have better performance when placed in the center of the wireless zone.

An example:
The NID to inside the house gets wired with a 4 pair CAT-5E cable. The DSL splitter is in the NID. Pairs #1, #2 and #3 would go to a standard 6 conductor phone jack and Pair #4 would go directly to the DSL modem.

Alarm Systems
These are usually connected via a special jack called an RJ31X. This jack should be installed at the telephone distribution location. When no plug is inserted, pair #1 is looped through the jack. When a plug is inserted, the alarm system can seize the line even if a phone is in use. The two extra pins can be used as part of a tamper circuit.

Modern Homes
A "Modern Home" is where structured wiring is in place. That may mean 2 cable outlets and 2 Cat-5 cables are in most rooms. Fiber can be added. IR controls can be added. A home automation system can be added. Security can be added. There are camera's, doorbell systems, drapery and shade control systems etc.