Hardware manual

Issue 8 Electra Elite
5 - 62 Installing Electronic Telephone Units
4.12 PRT(1)-U( ) ETU
4.12.1 Description
The PRT(1)-U( ) ETU is a Digital Trunk Interface that
provides for the termination of an ISDN-PRI line for voice
service only.
The PRT(1)-U( ) ETU supports AT&T 4ESS (Custom),
AT&T 5ESS (Lucent), DMS-100 (Custom or National
ISDN) and NI-2 protocols. Call-by-Call and Universal call
handling are also supported. Tip and Ring electrical fuses
are provided to comply with UL 1459 requirements.
Figure 5-35 PRT(1)-U( ) ETU