Lucent Technologies 8.2 Manuale Utente

Issue 1

April 2000

Features and technical reference 

1566

Trunks and Trunk Groups 

without attendant assistance. CO trunks typically connect your switch to the local 
central office, but they can also connect adjuncts such as external paging systems 
and data modules.

Use CPE trunks to connect adjuncts, such as paging systems and announcement or 
music sources, to the switch.

You can connect some types of equipment to the switch by trunks without 
administering a CPE trunk group. For example, trunk port interfaces can be 
assigned on system screens for Music-on-Hold Access (Feature-Related 
System Parameters screen) or voice and chime paging (Loudspeaker Paging 
and Code Calling Access screen).

DID trunks carry incoming calls directly from the local central office to your 
switch. These trunks transmit the digits your switch needs to route incoming calls 
to specific extensions. Use DID trunks when you want people calling your 
organization to dial individual users directly without going through an attendant or 
some other central point.

DIOD trunks are two-way trunks that transmit dialed digits in both directions. 
Thus, use DIOD trunks when you want a two-way trunk group with the 
convenience of direct inward dialing for incoming calls. DIOD trunks are used 
mostly outside North America, and typically they connect the switch to a local 
central office.

In North America, use tie trunks for applications that require two-way 
transmission of dialed digits. In the U.S., trunks that transmit digits in both 
directions are sometimes called “smart trunks” and are administered as T1 tie 
trunks. 

An FX trunk is essentially a CO trunk that connects your switch directly to a 
central office outside your local exchange area. Use FX trunks to reduce long 
distance charges if your organization averages a high volume of long-distance 
calls to a specific area code.