Project: use non-standard twisted pair phone wire for a serial terminal.

Cable: "ptt 278 4x2x0.6"

1. blue/slate
2. orange/yellow
3. gray/white
4. brown/violet

Status before: 

SHELL (chassis gnd) ----------- violet
2 (TxD) ----------------------- slate
3 (RxD) ----------------------- white
4 (RTS) ----------------------- yellow
5 (CTS) ----------------------- orange
6 (DSR) ----------------------- brown --+
7 (SG)  ----------------------- blue    |
8 (DCD) ----------------------- to 6 ---+
20 (DTR) ---------------------- gray
22 (RI) ----------------------- (nc)

from http://ftp.unina.it/pub/electronics/REPAIR/F_Pinouts2.html

      6.8.6) DB-25 (25 pin) to RJ45 (10 pin)


SHELL (chassis gnd) ----------- 4 (chassis gnd)
2 (TxD) ----------------------- 5 (TxD)
3 (RxD) ----------------------- 6 (RxD)
4 (RTS) ----------------------- 3 (RTS)
5 (CTS) ----------------------- 8 (CTS)
6 (DSR) ----------------------- 2 (DSR)   
7 (SG)  ----------------------- 7 (SG)
8 (DCD) ---------------------- 10 (DCD)
20 (DTR) ---------------------- 9 (DTR)
22 (RI) ----------------------- 1 (RI)

after the change the pairs are used as recommended in eia 568a, carrying
serial data as follows:

6 (DSR) ----------------------- 1 (DSR) ---+ pair 3 w
4 (RTS) ----------------------- 2 (RTS) ---+        gry
SHELL (chassis gnd) ----------- 3 (chassis gnd)---+ ye
2 (TxD) ----------------------- 4 (TxD) -+ pair 1 |pair 2
3 (RxD) ----------------------- 5 (RxD) -+ bl/slt |
7 (SG)  ----------------------- 6 (SG) -----------+ or
5 (CTS) ----------------------- 7 (CTS) ---+ pair 4 vi
20 (DTR) ---------------------- 8 (DTR) ---+        br
8 (DCD) ----------------------- (nc)
22 (RI) ----------------------- (nc)