Hardware manual

Electra Elite Issue 8
System Hardware Manual 5 - 29
4.3 COI(4)/(8)-U( ) ETU
4.3.1 Description
The COI(4)/(8)-U( ) ETU provides the Central Office
interface. The COI ETU contains circuitry for outside ring
detection, holding, dialing, and control functions.
This ETU can provide a CAMA trunk for Enhanced E911.
The COI(8)-U( ) ETU provides identical circuits to serve
up to eight CO trunks that can be any combination of
Loop Start or Ground Start with DTMF signaling. The
COI(4)-U
( ) is for Loop Start trunks with DTMF signaling
only. ETU Tip and Ring electrical fuses are provided to
comply with UL 1459 requirements. Refer to Figure 5-16
COI(8)-U( ) ETU.
Figure 5-16 COI(8)-U( ) ETU