Monday, September 21, 2009

Back-To-Back cables for T1/E1/BRI/E&M

This is a simple reference to make back-to-back connections. Very useful in lab scenarios with voice gateways emulating the PSTN.


Thanks to Aashish for this :





T1/E1 crossover (for PRI and CAS back-to-back connection): 

RJ-45 ----- RJ-45
   1  -----  4
   2  -----  5
   4  -----  1
   5  -----  2


RJ-45 ----- DB-15
   1  -----   1
   2  -----   9
   4  -----   3
   5  -----  11


DB-15 ----- DB-15
   1  -----   3
   3  -----   1
   9  -----  11
  11  -----   9



ISDN BRI crossover (for BRI back-to-back connection): 


RJ-45 ----- RJ-45
   3  -----  4
   4  -----  3
   5  -----  6
   6  -----  5



Analog E&M (for analog E&M back-to-back connection):


RJ-45, 2-wire audio
   1  -----  8
   2  -----  7
   4  -----  5
   5  -----  4
   7  -----  2
   8  -----  1
         
RJ-45, 4-wire audio
   1  -----  8
   2  -----  7
   3  -----  5
   4  -----  6
   5  -----  3
   6  -----  4
   7  -----  2
   8  ------ 1



Analog FXS/FXO back-to-back connection:


RJ-11 ----- RJ-11
   2  -----   3
   3  -----   2




    RJ-11 connector
    ===============
         _____
        /    /|
       /4321/ |
      /____/  |
      ||||||  /
      |    | /
      |_--_|/
        \_\




    RJ-45 connector
    ===============
     _________
    /        /|
   /87654321/ |
  /________/  |
  ||||||||||  /
  |   __   | /
  |__|  |__|/
      \_\
                             



    DB-15 male connector
    ====================


pin 1 _______________ pin 8
     /. . . . . . . .\
     \ . . . . . . . /
pin 9 \_____________/ pin 15