Lucent Technologies 8.2 User Manual

Issue 1

April 2000

Features and technical reference 

1569

Trunks and Trunk Groups 

A trunk is named for its transmission characteristics. For example, trunks are 
always classified by the direction of the traffic they allow:

■

One-way incoming trunk 

—

 A local trunk that can be selected (seized) by 

the far-end connected switch.

■

One-way outgoing trunk 

—

 A trunk that can be seized by the local switch 

to call the far-end switch.

■

Two-way trunk 

—

 A trunk that can be seized by either of the connected 

switches.

Another transmission characteristic is signaling, which is the transmission of 
supervision, address, alerting, or other switching information. Supervisory 
signaling establishes or sets up the connection of the local switch to the distant 
switch. In general, supervisory signaling has 2 phases:

■

Seizure signal 

—

 The originating office’s signal for a request for service 

from the distant office.

CO, FX, WATS

Incoming

Outgoing

Two-way

Either

Any kind of voice or 
data traffic.

No

CPE

N.A.

Either

Any kind of voice or 
data traffic.

No

DID

Incoming

Either

Only voice and 
voice-grade data.

Yes

DIOD

Incoming

Outgoing

Two-way

Either

Any kind of voice or 
data traffic.

Only for 
incoming calls

PCOL

Incoming

Outgoing

Two-way

Analog 
only

Only voice and 
voice-grade data.

No

Tie, Access

Incoming

Outgoing

Two-way

Either

Any kind of voice or 
data traffic.

Yes