modular connector (Used for ethernet/telephone)

http://en.wikipedia.org/wiki/Modular_connector#6P2C

http://en.wikipedia.org/wiki/Registered_jack#Registered_jack_types

6P6C family

Telephone

Do note that telephone plugs typically are called RJ11 (6P2C) , but most are actually sold as 6P4C.

In the product page for Oregon electronics, we can see that they refer to 6P4C as RJ11, and 6P6C as RJ12. This is technically inaccurate, but it's how the industry refers to these plugs these days.

diagrams


    6P2C PORT (Telephone. Typically called as RJ11 ):
    (6 Possible Contacts, 4 Pin Contacts Used)
            _____
          _|     |_
     ____|         |____
    |                   |
    |                   |
    |                   |
    |_ [] [] 2 1 [] [] _|

    If Twisted Pairs:
        pair1: pin 1&2

    http://en.wikipedia.org/wiki/Registered_jack#Registered_jack_types



    6P4C PORT (Telephone. Typically called RJ12):
    (6 Possible Contacts, 4 Pin Contacts Used)
            _____
          _|     |_
     ____|         |____
    |                   |
    |                   |
    |                   |
    |_  [] 4 3 2 1 []  _|

    If Twisted Pairs:
        pair1: pin 3&2, 
        pair2: pin 1&4 

    http://en.wikipedia.org/wiki/Registered_jack#Registered_jack_types



    6P6C PORT (Telephone. Pretty rare):
    (6 Possible Contacts, 6 Pin Contacts Used)
            _____
          _|     |_
     ____|         |____
    |                   |
    |                   |
    |                   |
    |_   6 5 4 3 2 1   _|

    If Twisted Pairs:
        pair1: pin 3&4, 
        pair2: pin 2&5,
        pair3: pin 1&6

    http://en.wikipedia.org/wiki/Registered_jack#Registered_jack_types

8P8C (e.g. Ethernet Plug)

Typically referred to as an RJ45 plug

http://en.wikipedia.org/wiki/Modular_connector#8P8C

diagrams


    8P8C (e.g. Ethernet) PORT:
    (8 Possible Contacts, 8 Pin Contacts Used)
            _____
          _|     |_
     ____|         |____
    |                   |
    |                   |
    |                   |
    |_ 8 7 6 5 4 3 2 1 _|

    http://en.wikipedia.org/wiki/TIA/EIA-568#Wiring

    Cat5 Twisted Pairs:
        pair1: 5&4
        pair2: 6&3
        pair3: 8&7
        pair4: 2&1

note:

Don't forget the pinout of cat5 with an RJ45 connector - the pairs are not wired to the pins in order. The pairing is AABCCBDD --n1ist