DB9 to RJ11 Connector Pinout - AllPinouts

From [1] is a interface for RS-232 from DB-9S (Female) to RJ11 to telephone cable to RJ11 to DB-9P (Male). It is not known whether this is any type of standard. Note that if this is accidentally connected to a telephone, then one telephone wire is grounded, and TXD and RXD are no connect. Everything should survive.

6 pin RJ11, RJ14 female connector at the phone and wallet socket (Jack).

6 pin RJ11, RJ14 male connector at the cable (Plug).

DB9S (female pins) to jack:

RJ11	DB9S	Function
1	NC	-
2	2	RXD
3	5	GND
4	NC	-
5	3	TXD
6	NC	-

DB9p (male pins) to jack:

RJ11	DB9P	Function
1	NC	-
2	3	TXD
3	NC	-
4	5	GND
5	2	RXD
6	NC	-

Phone cable, please note that this is a crossover cable, with pins 1 and 6 not used:

RJ11	RJ11
1 or NC	6 or NC
2	5
3	4
4	3
5	2
6 or NC	1 or NC

Here is a variation that is also used. It provides two grounds:

DB9S (female pins) to jack:

RJ11	DB9S	Function
1	NC	-
2	2	RXD
3	5	GND
4	5	GND
5	3	TXD
6	NC	-

DB9p (male pins) to jack:

RJ11	DB9P	Function
1	NC	-
2	3	TXD
3	5	GND
4	5	GND
5	2	RXD
6	NC	-