Lucent Technologies DEFINITY Enterprise Communication Server Release 8.2 Administrators Guide

							DEFINITY ECS Release 8.2
Administrator’s Guide  555-233-506  Issue 1
April 2000
Features and technical reference 
1567 Trunks and Trunk Groups 
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IP Trunks — Internet Protocol Trunks
IP trunks allow DEFINITY ECS to route voice calls and faxes over a local- or 
wide-area TCP/IP network. Use IP trunks to reduce long-distance charges by 
routing calls over the Internet or your intranet. 
NOTE:
The origin and destination switches must both have the special hardware and 
software needed to route telephone calls over IP networks. Refer to ‘‘
IP 
trunk service’’ on page 1383 for more information.
ISDN — Integrated Services Digital Network
ISDN trunks are digital trunks that can integrate voice, data, and video signals and 
provide the bandwidth needed for applications such as high-speed data transfer 
and video conferencing. ISDN provides end-to-end digital connectivity and uses a 
high-speed interface that provides service-independent access to switched 
services. Through internationally accepted standard interfaces, an ISDN provides 
circuit or packet-switched connectivity within a network and can link to other 
ISDN-supported interfaces to provide national and international digital 
communications. ISDN trunks can also efficiently combine multiple services on 
one trunk group.
PCOL — Personal Central Office Line
A personal central office line is one dedicated trunk that links a group of phones to 
the local central office or to another switch in a private network. A PCOL group 
can have 1–16 phones, and each phone can have one or more appearances for the 
personal central office line. You may administer a PCOL group as a CO, FX, or 
WATS trunk group. Use a PCOL line when one or more users need a direct, 
dedicated connection to the public network or to another switch.
Tie
Tie trunks connect a switch to a central office or to another switch in a private 
network. These trunks transmit dialed digits with both outgoing and incoming 
calls. Thus, incoming calls over a tie trunk can be routed directly to the extension 
the caller dialed. Tie trunks are frequently used in private networks; in addition, 
use tie trunks when you want a two-way trunk group with the convenience of 
direct inward dialing for incoming calls.
Tie trunks that connect private network switches are “universal. “This means that 
the trunks can be administered with a variety of translation encodes. The 
originating switch can recognize any start dial signal (precise dial tone, wink start, 
or delay dial) that the terminating switch sends. If the originating switch does not  
						

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receive one of these start dial signals, it can be administered to send digits after an 
administered interval. (This time-out interval is the amount of time that the 
originating switch waits before sending digits.)
Analog tie trunks
The number of tie trunks in a connection and the technology of any multiplex 
systems used in the facilities affect the maximum data transfer rate. Generally, for 
transfer rates up to 300 bps, a connection can have 5 tie trunks in tandem. For data 
rates of 301–2,400 bps, a connection can have up to 3 tie trunks in tandem. For 
data rates of 2,401–4,800 bps, a connection can have up to 2 tie trunks in tandem.
Analog tie trunks used in unswitched connections can support up to 9,600 bps.
Digital tie trunks
The digital tie trunk is a high-speed and high-volume trunk interface to a T1 or E1 
carrier. It uses a digital signal level 1 (DS1) protocol. By multiplexing 24 64-kbps 
digital channels onto a single 1.544-Mbps T1 carrier, or 32 64-kbps digital 
channels onto a single 2.048-Mbps E1 carrier, DS1 offers an economical 
alternative to the analog tie trunk as well as a high-speed fully digital (without 
modems) connection between the switches.
The maximum per-channel data rate for DS1 is 64 Kbps, and DS1 trunks can carry 
voice, voiceband data, or high-speed data communications.
WATS — Wide Area Telecommunications 
Service
Outgoing WATS service allows calls to certain areas (“WATS bands”) for a flat 
monthly charge. Incoming WATS trunks allow you to offer toll-free calling to 
customers and employees.
Applications for different trunk types
To help you select the right type of trunk for a specific application, the following 
table gives you an overview of key characteristics of different trunk groups. 
Remember that all analog trunks can carry only voice and voice-grade data. 
						

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Transmission and supervisory signaling
A trunk is named for its transmission characteristics. For example, trunks are 
always classified by the direction of the traffic they allow:
nOne-way incoming trunk — A local trunk that can be selected (seized) by 
the far-end connected switch.
nOne-way outgoing trunk — A trunk that can be seized by the local switch 
to call the far-end switch.
nTwo-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:
nSeizure signal — The originating office’s signal for a request for service 
from the distant office.
Type of trunk DirectionAnalog or 
Digital? Traffic supportedTransmits 
digits?
CO, FX, WATS Incoming
Outgoing
Two-wayEither 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-wayEither Any kind of voice or 
data traffic.Only for 
incoming calls
PCOL Incoming
Outgoing
Two-wayAnalog 
onlyOnly voice and 
voice-grade data.No
Tie, Access Incoming
Outgoing
Two-wayEither Any kind of voice or 
data traffic.Yes 
						

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nStart-dial signal — The distant office’s acknowledgment that it is ready to 
accept dialing from the originating office.
Seizure signals
Ear & Mouth (E&M) supervision
E&M supervision is a symmetric signaling scheme used on private network 
trunks. DC voltage levels are sent over E&M leads, which are separate from the 
transmission path. E & M signals indicate on-hook and off-hook states for each 
end of the connection path.
Ear & Mouth (E&M) supervision on digital trunks
DIOD trunk groups support Continuous and Pulsed E&M Signaling that allows 
you to make and receive calls over Brazil pulsed or continuous E&M signaling 
trunks and Hungarian pulsed E&M signaling trunks. Refer to DEFINITY ECS 
Application Notes for Type Approval for more information.
Ground-start (GS) supervision
Ground-start signaling is a supervisory signaling scheme used on public network 
trunks in which ground is applied on the tip (T) lead by the CO and on the ring (R) 
lead by the switch. For example, the calling switch on a call to a CO seizes the 
outgoing trunk by placing a ground on the trunk interface R lead. The CO 
recognizes the trunk seizure as a request for service and grounds the trunk T lead 
to indicate to the calling switch that the CO is ready to receive digits. Ground-start 
signaling is superior to loop-start signaling (described below) for the following 
reasons:
nThe switch can make trunks busy to outgoing calls almost immediately, 
because the tip ground seizure by the distant switch minimizes the interval 
during which a two-way trunk can be seized from both ends (called glare). 
nGround-start signaling allows answer supervision, a positive indication that 
a distant switch has disconnected from a call. Answer supervision has 2 
benefits:
— Callers who remain off-hook after completing a call won’t be 
connected to central office dial tone. For example, this prevents a 
restricted station from making an unauthorized call after placing an 
authorized call using the attendant.
— By holding the trunk busy until the central office disconnects, 
another switch cannot seize the trunk and be connected to the CO 
party of the previous call. 
						

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nLoop-start (LS) supervision — A supervisory signaling scheme used 
between a telephone and a switch in which the telephone or far-end office 
completes the current path formed by the trunk wires. The circuit provides 
one signaling state when it is open and another when it is closed. A third 
signaling state is achieved by changing the direction or magnitude of 
current in the loop. The preferred method of loop-start signaling is reverse 
battery signaling. Disconnect times when using loop-start signaling can 
result in delays of up to 10–20 seconds. Glare, as described in ground-start, 
is possible.
Loop-start signaling does not provide answer supervision. This lack can 
open a potential for toll fraud in some situations, especially when incoming 
calls are forwarded off-net. Loop-start is used with analog DIOD trunks, 
but in general try to use loop start only with one-way trunks.
nReverse Battery (RB) supervision — A supervisory technique on 
one-way trunks that uses open and closure signals from the originating end 
and reversals of battery and ground from the terminating end (normally 
used on direct inward dialing trunks).
Start-dial signals
Network trunks operate as automatic, immediate start, dial tone, wink start, or 
delay dial according to the type of start-dial signal (alerting) the switch sends out 
or expects to receive. The different transmissions of alerting are:
nAutomatic — The originating switch sends no digits or start dial signal 
and expects the terminating switch to complete the call. The call usually is 
completed by the attendant or other service such as Centralized Attendant 
Service (CAS).
nImmediate start — The originating switch sends digits immediately 
without waiting for a start dial signal from the terminating switch.
nDial tone — The terminating switch sends precise dial tone to the 
originating switch. This indicates that the terminating switch is ready to 
receive digits.
nWink start — The terminating switch sends a wink start (momentary 
off-hook) signal to the originating switch. This indicates that the 
terminating switch is ready to receive digits.
nDelay dial — The terminating switch sends a delay dial signal (an 
off-hook signal followed by an on-hook signal) to the originating switch. 
This indicates that the terminating switch is ready to receive digits. 
						

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Types of address transmission
In addition to seizure and start dial signals, switches have to transmit the digits 
and characters for telephone numbers. This is called address transmission. Three 
types of signaling are available: 
nDial Pulse (DP) addressing — A method of signaling that consists of 
regular momentary interruptions of a direct or alternating current at the 
sending end. The number of interruptions corresponds to the value of a 
digit or character (alternating current is not used by switches). The 
interruptions usually are produced by a rotary telephone dial, or may be 
produced by a sender in a switching system.
nDual Tone Multifrequency (DTMF) addressing — Signaling 
arrangements (commonly known as touch-tone) that consist of two, 
simultaneous, dialing signals. One tone is from a low group of four 
frequencies. The other tone is from a high group of four frequencies. Both 
tones correspond to digits, letters, or characters (0–9, A–Y, or * and #). One 
of the tones (1,633 Hz) from the high group is a spare.
nMultifrequency (MF) addressing — Signaling arrangements that make 
use of only 2 frequencies out of 6 to represent 10 decimal digits (0– 9) and 
5 auxiliary signals. MF signals are used for called number addressing, 
calling number identification. They also report whether the far end is 
ringing or busy.
Analog vs. digital trunks
Analog trunks carry voice and voiceband data communication. “Voice” means that 
sound of any kind is transformed into electrical waveforms and transmitted within 
an approximate bandwidth of 300 Hz to 3,400 Hz. “Voiceband data” means that 
data is transmitted within the voiceband and requires a conversion resource 
(modem) at both ends of the connection. The data-transmission rate for analog 
trunks depends on the data-handling capability of the modems in the connection. 
Digital trunks represent both sound and data as 0’s and 1’s and can be configured 
to carry any kind of voice or data traffic. Digital trunks connect to a DS1 circuit 
pack and provide a T1 or E1 carrier. DS1 service provides an interface for CO, 
FX, DID, tie, and WATS trunks. The DS1 interface supports incoming and 
outgoing dial types of ground-start, loop-start, auto/auto, auto/delay, auto/immed, 
and auto/wink. Signaling may be robbed-bit or common-channel depending on 
the trunk type and whether the dial-type is incoming or outgoing. The interface 
may be used to connect the switch to a toll office directly using wink-start tie 
trunks for two-way access to the toll network.
Supervision, addressing, and alerting methods have been carried over to digital 
trunks, which use basically the same signaling scheme as analog trunks when 
establishing a call. These schemes are handled in a variety of ways to indicate  
						

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particular calling states, such as on-hook, off-hook, ringing, not ringing, and so 
on, by using A and B bit-timed signaling. A and B bits carry a 0 or 1 depending on 
the type of trunk, the near-end channel unit type, far-end channel type, the 
condition of the trunk (open loop, loop closure, reverse battery, and so on), and 
whether it is transmit or receive signaling. In addition to the above, refer to ‘‘
DS1 
Circuit Pack’’ on page 599 for trunk-related terms associated with DS1 trunk 
interfaces.
Interactions
nBrazil Block Collect Call
In both continuous and pulsed E&M signaling, Block Collect Call is not 
included.
nPersonal Central Office Line (PCOL)
PCOL trunks cannot use continuous, pulsed, or discontinuous E&M.
Related topics
Refer to the DEFINITY ECS System Description for information on the types of 
circuit packs available and their capacities. This manual also lists the maximum 
number of trunks and trunk groups for each system configuration.
Refer to ‘‘
Managing trunks’’ on page 337 for administration procedures.
Refer to ‘‘
DS1 Trunk Service’’ on page 1317 for detailed information on Digital 
Signal Level 1 trunk service.
Refer to ‘‘
IP trunk service’’ on page 1383 for detailed information about sending 
voice calls over IP networks.
Refer to ‘‘
ISDN service’’ on page 1394 for detailed information about Integrated 
Services Digital Network trunks.
Voice Message Retrieval
Voice Message Retrieval allows attendants, phone users, and remote-access users 
to retrieve Leave Word Calling (LWC) and Call Coverage messages. 
						

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Detailed description
Voice Message Retrieval is only used for the retrieval of messages. When a 
terminal is in Voice Message Retrieval mode, it cannot be used to make calls or 
access other features. Voice Message Retrieval can be used to retrieve your own 
messages or messages for another user. However, a different user’s messages can 
only be retrieved by a user at a phone or attendant console in the coverage path, by 
an administered system-wide message retriever, or by a remote-access user when 
the extension and associated security code are known. The number of 
simultaneous Voice Message Retrieval users possible depends on the number of 
speech-synthesizer circuit packs used in the system.
Certain phones and attendants can be designated for system-wide message 
retrieval. These system-wide retrievers are the same as those used for Display 
Message Retrieval and have the same privileges. Voice Message Retrieval cannot 
be accessed from rotary phones.
You can use the system to restrict unauthorized users from retrieving messages. 
Use the Lock function to restrict a phone and the Unlock function to release the 
restriction. Users activate Lock by dialing a system-wide access code. They cancel 
Lock by dialing a system-wide access code and then an Unlock security code 
unique to the phone. These functions only apply to the phone where the function 
is active. The system-wide access codes and security code used for the Lock and 
Unlock functions are the same as those used for LWC message retrieval by 
display. You can assign a status lamp to show the lock status of the phone.
Interactions
nAUDIX Interface
Retrieval of LWC messages via Voice Message Retrieval is separate and 
distinct from retrieval of messages via INTUITY. LWC messages left for a 
principal on AUDIX cannot be accessed via Voice Message Retrieval. 
However, the caller of Voice Message Retrieval is informed of any new 
messages for the principal on AUDIX:
— The Voice Message Retrieval voices that there are AUDIX 
messages.
— The Display Message Retrieval displays “Message Center AUDIX 
Call.”
If your system has a voice-synthesizer circuit pack and LWC Activation is 
active, users can retrieve messages from two locations:
— Users can retrieve LWC messages with Voice Message Retrieval.
— Users can retrieve all other messages with AUDIX. 
						

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If you do not have a TN725B speech-synthesizer board, non-display phone 
users cannot retrieve LWC messages sent via the LWC button on a phone.
nBridged Call Appearance
Voice Message Retrieval on a Bridged Call Appearance functions the same 
as if it were activated by the primary extension associated with the bridged 
call appearance.
nLeave Word Calling
Voice Message Retrieval enhances LWC by allowing any authorized 
touch-tone phone user to retrieve messages.
Related topics
Refer to ‘‘
Audible Message Waiting’’ on page 1152 for information about letting 
users know they have messages.
Refer to ‘‘
Feature Access Code’’ on page 619 for information about and field 
descriptions on the Feature Access Code screen. Complete the LWC Message 
Retrieval Lock, LWC Message Retrieval Unlock, Voice Coverage Message 
Retrieval Access Code, and Voice Principal Message Retrieval Access Code fields 
on this screen to administer voice message retrieval.
Refer to ‘‘
Feature-Related System Parameters’’ on page 632 for information about 
and field descriptions on the Feature-Related System Parameters screen. 
Complete the Stations With System-Wide Retrieval Permission and Message 
Waiting Lamp Indicates Status For fields on this screen to administer voice 
message retrieval.
Refer to ‘‘
Station’’ on page 882 for information about and field descriptions on 
the Station screen. Complete the Security Code field on this screen to administer 
voice message retrieval. 
						

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Voice Messaging Systems
DEFINITY ECS supports several Lucent voice or multimedia messaging systems. 
These systems allow users to send, retrieve, store, and forward messages, as well 
as perform many other tasks associated with messages. In addition to supporting 
multiple AUDIX systems, DEFINITY can have multiple hunt groups associated 
with a single AUDIX system. This allows partitioning of the voice ports into 
different hunt groups and different coverage paths to cover different voice ports. 
Thus voice ports can be reserved for particular users or groups of users (for 
example, those that use unique coverage paths). 
The following features do not use coverage paths:
nTransfer into AUDIX with the feature access code or the GOTO COVER 
button
nLast Call
If a local AUDIX and a remote AUDIX use the same hunt-group numbers, calls 
route to the local hunt group.