3Com MSR 20, MSR 30, MSR 50 Pinouts of E&M interface cable Bell V 4-wire, RING0 RING1 TIP1 TIP0

MIM-2FXS/MIM-2FXO/MIM-2E&M and MIM-4FXS/MIM-4FXO/MIM-4E&M 115

Figure 131 E&M interface cable (Bell V 4-wire)

PBX					Router
					on-hook
			E	M 7	off-hook
	detect
				on-hook
-48 V						-48 V
				2
off-hook			M			-48 V
				E
					detect
		on-hook

T0T0

4- wire

R0R0

voice signal

T1T1

R1R1

6

3 4- wire voice signal

5

4

Table 75 Pinouts of E&M interface cable (Bell V 4-wire)

Router side
RJ-45 Pin	RJ-45 interface signal	Signal at switch side (Bell V 4-wire)
1	SB (negative power supply)	-
2	E	M
3	RING0	RING0
4	RING1	RING1
5	TIP1	TIP1
6	TIP0	TIP0
7	M	E
8	SG (negative power supply	-
	ground)

n Because it is hard to determine the type of the switch to be connected and its connectors, interface cables of MIM-2E&M/MIM-4E&M modules have to be prepared according to the on-spot conditions or by the user. To ensure the EMC of the Router, install a ferrite core near the connector of the prepared E&M module interface cable by the router side.

Connecting the Interface Cable

c

CAUTION:

■Some measures are taken to protect MIM-2FXS/MIM-2FXO/MIM-2E&M and MIM-4FXS/MIM-4FXO/MIM-4E&M. Still, you are recommended to install a special lightning arrester at the input end of each connection cable to obtain better lightning protection effect when the cable is led outdoors;