PHONE WIRE PINOUT
RJ11 Telephone · AllPinouts
6 pin RJ11, RJ14, RJ25 female connector at the phone and wallet socket (Jack). 6 pin RJ11, RJ14, RJ25 male connector at the cable (Plug). The six-position plug and jack commonly used for telephone line connections may be used for RJ11, RJ14 or even RJ25, all of which are actually names of interface standards that use this physical connector.
How to Wire a Phone Jack (Voice or Telephone RJ-11 thru RJ-14)
How to Wire a Phone Jack (Voice or Telephone RJ-11 thru RJ-14) (USOC Wiring Diagram) Telephone wiring for a phone outlet is typically either 1, 2 or 3 pairs (2, 4, or 6 conductor). Most cable nowadays is UTP (unshielded twisted pair). There may be instances where you may need to connect to or transpose from the old "quad" cable.
RJ11 Phone to RJ45 Jack - tombuildsstuffspot
It would make sense to wire ports following the USOC specification but by using T568A a cable can later be easily switched from voice to data or vice versa in the future. You'll notice that Line 1 and Line 2 on both T568A and USOC are identical. If you have a two line phone, you can plug it directly into a T568A wired jack and both lines will work.
Telephone plug - Wikipedia
A telephone plug is a type of connector used to connect a telephone set to the telephone wiring inside a building, establishing a connection to a telephone network. It is inserted into its counterpart, a telephone jack, commonly affixed to a wall or baseboard standard for telephone plugs varies from country to country, though the RJ11 modular connector has become by far the most common.