Cisco 1605-R How To Use Manual page 55

You can distinguish between WIC36 and WIC models of a BRI WAN interface card by the
location and labeling of the LEDS, and the number and location of cutouts in the faceplate.
1-Port BRI S/T WAN Cards (WIC36-1B-S/T, WIC-1B-S/T)
The 1-Port ISDN-BRI WAN interface cards (WIC36-1B-S/T, WIC-1B-S/T) connect to an
ISDN WAN through an external NT1 device. (See Figure 3-5 and Figure 3-6.) This
interface is also known as an S/T interface.
1-Port BRI with NT1 WAN Cards (WIC36-1B-U, WIC-1B-U)
The 1-Port ISDN-BRI with NT1 WAN interface cards (WIC36-1B-U, WIC-1B-U) connect
to an ISDN WAN using a built-in NT1 device. (See Figure 3-7 and Figure 3-8.) This
interface is also known as a U interface.
Figure 3-5
1-Port BRI S/T WAN Cards (WIC36-1B-S/T, WIC-1B-S/T)
1-Port ISDN BRI WAN Interface Card (S/T Interface) (WIC36-1B-S/T)
BRI S/T port
LEDs
B1
B2
SEE MANUAL BEFORE INSTALLATION
Connecting WAN and Voice Interface Cards to a Network 3-7
BRI
S/T