11
The S0 Module 420
The S0 module features the following inter-
faces:
1 External S0 interface S0 X/1(ISDN basic ac-
cess as a point-to-multipoint or point-to-
point connection)
1 Switchable internal / external S0 interface
S0 X/2
(external: ISDN basic access as a point-to-
multipoint or point-to-point connection,
internal: point-to-multipoint connection)
Slots: X=1 to 4, freely optional
Schalter
S201
Schalter
S202
Figure 7: S0 module 420 with the terminators
b2
a2
b1
a1
12
3
4
external S0
b1
a1
b2
a2
internal S0
12
3
4
S0 X/1
exter
nal
S0 X/2
switchable S0
a1
b1
a2
b2
Western plug to
the NTBA or to
the IAE socket
b2: white
a2: yellow
b1: brown
a1: green
1.....8
3: a2
4: a1
5: b1
6: b2
external S0
ext.
int. S0
ext./int.
ext.
S4200
S4101
S4201
terminators
Figure 8: Pin assignments of the
S0 module 420
