Juniper SRX Series Manual page 155

Table 74 on page 137 shows the pin assignments of the RJ-45 cable (RJ-45 to 4 X RJ-11).
Table 74: RJ-45 Cable (RJ-45 to Four RJ-11 Connectors) Pinout Details
RJ-45 Pin Number Connections
1 Tip 1
2 Ring 1
3 Tip 2
4 Tip 0
5 Ring 0
6 Ring 2
7 Tip 3
8 Ring 3
Figure 36 on page 138 shows the RJ-45 cable design that connects to four RJ-11 cable connections.
RJ-11 Pin Number Connections
3 Tip 1 of 1st port
4 Ring 1 of 2nd port
3 Tip 2 of 3rd port
3 Tip 0 of 1st port
4 Ring 0 of 1st port
4 Ring 2 of 3rd port
3 Tip 3 of 4th port
4 Ring 3 of 4th port
Plug Number
P1
P2
P3
P4
137