Lucent Technologies DEFINITY Enterprise Communications Server Release 8.2 Administration For Network Connectivity Manual

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B Private Networking
This appendix contains five main sections: (1) a description of Distributed Communications 
System (DCS) and the features that can be used transparently on a DCS network, (2) a 
description of ISDN Plus networking capability, (3) a description of QSIG and its features, (4) a 
brief description of Centralized Voice Mail with Mode codes, and (5) a brief description of Japan 
TTC private networking protocols.
Contents of this Appendix
Distributed Communications System  (page 312)
ISDN Feature Plus  (page 355)
QSIG  (page 360)
Centralized Voice Mail Via Mode Code  (page 395)
Japan TTC Q931-a Private Networking Protocols  (page 400) 
						

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Distributed Communications System 
Distributed Communications System (DCS) allows you to configure 2 or more 
switches as if they were a single, large DEFINITY ECS. DCS provides attendant and 
voice-terminal features between these switch locations. DCS simplifies dialing 
procedures and allows transparent use of some of the DEFINITY ECS features. 
(Feature transparency means that features are available to all users on DCS regardless 
of the switch location.)
Configuring a DCS network is a complex process that involves 4 major steps:
•Planning your DCS network
•Connecting the physical equipment in the network
•Administering the physical layer (hardware connections)
•Administering the link layer to create a DCS
Description of DCS
DCS network configurations can be:
•TCP/IP DCS network — A DCS network configured with 2 or more switches 
using TCP/IP (PPP or 10/100BaseT Ethernet) signaling for transporting DCS 
feature transparency information.
•Traditional DCS network — A DCS network configured with 2 or more switches 
using BX.25 signaling for transporting DCS feature transparency information.
•D-channel DCS network (private network only) — A DCS network that includes 
DEFINITY ECS using the ISDN-PRI D-channel DCS transparency information 
(D-channel signaling). ISDN-PRI facilities with this type of network use only 
private-line facilities.
•D-channel DCS network (public network access/egress) — A DCS network that 
includes DEFINITY ECS using D-channel signaling. At least one of these 
ISDN-PRI facilities uses a public network ISDN-PRI.
•Integrated DCS network (private network only) — A DCS network that contains a 
variety of switches using TCP/IP, BX.25, or D-channel signaling methods. At 
least one DEFINITY ECS serves as an ISDN-PRI DCS Gateway node. This node 
can interwork DCS transparency information between the three signaling 
protocols.
An ISDN-PRI DCS Gateway node provides backward compatibility to existing 
traditional DCS networks.
•Integrated DCS network (public network access) — The same as D-channel DCS 
Network (Private Network Only), but the D-channel of at least one ISDN- PRI 
facility uses a public network ISDN-PRI. 
						

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DCS Features
Once you have connected and set up your DCS network, you can provide the 
following features across the network:
Alphanumeric Display for Terminals 
This feature allows calling-name display, called-name display, and miscellaneous 
identifiers to be transferred from a terminal on one node to a terminal on another 
node.
Attendant Control of Trunk Group Access 
DCS Attendant Control of Trunk Group Access allows an attendant at any node in 
the DCS to control an outgoing trunk group at an adjacent node in the cluster. The 
attendant uses a remote-tgs feature button on the console for this purpose.
To use this feature, you must have a DCS Trunk Group between the local and 
remote switches, and the trunks in that trunk group cannot insert digits on 
incoming calls. If you need digit insertion on these trunks, it should be added on 
the outgoing trunk based on the dialed string.
Note:DCS Attendant Control of Trunk Group Access is not available if 
you are using D-channel DCS.
Attendant Direct Trunk Group Selection 
DCS Attendant Direct Trunk Group Selection allows attendants at one node to 
have direct access to an idle outgoing trunk at a different node in the DCS. This 
feature functions the same as regular Direct Trunk Group Selection. However, the 
attendant uses a remote-tgs feature button on the console for this purpose.
Note:DCS Attendant Direct Trunk Group Selection is not available if you 
are using D-channel DCS.
To use this feature, you must have a DCS Trunk Group between the local and 
remote switches, and the trunks in that trunk group cannot insert digits on 
incoming calls. If you need digit insertion on these trunks, it should be added on 
the outgoing trunk based on the dialed digits.
You can assign a Trunk Hundreds Select button to access a trunk group at the local 
node or a trunk group at a remote node. A Trunk Group Select button assigned to 
access a remote node is referred to as a remote Trunk Hundreds Select button. 
Pressing a remote Trunk Group Select button is the same as dialing the tie trunk 
group access code for the remote node and the trunk access code of the selected 
trunk.
Attendant Display 
The DCS attendant console displays calling-party ID and called-party ID 
information for calls to and from remote switches in the network. 
						

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Automatic Callback 
DCS Automatic Callback allows a user at one node to make an automatic callback 
call to a user at another node in the DCS. 
A DCS Automatic Callback call can be initiated from a terminal at one node to a 
terminal at another node in the same way as if at a local node under the following 
conditions.
~If the called party is at a System 85, Generic 2, or Enhanced DIMENSION 
PBX node, the callback call can only be activated if the called node is 
returning busy tone or special audible ringback.
~If the called party is at a Generic 3, Generic 1 or System 75 node, the callback 
call can be activated if the called node is returning busy tone, Call Waiting 
ringback tone, or ringback tone.
~The calling party must disconnect within 6 seconds after hearing the 
confirmation tone for Automatic Callback activation.
Note:If the calling party is on a System 85, Generic 2, or Enhanced 
DIMENSION PBX node and is unable to receive the callback call 
(for example, a busy single-line voice terminal without Call 
Waiting), Automatic Callback is reactivated by the calling party’s 
node. If the calling party is on a Generic 3, Generic 1, or System 75 
node and is unable to receive the callback call, the callback call is 
canceled.
Automatic Circuit Assurance 
DCS Automatic Circuit Assurance (ACA) allows a voice-terminal user or 
attendant at a node to activate and deactivate ACA referral calls for the entire DCS 
network. This transparency allows the referral calls to originate at a node other 
than the node that detects the problem.
If referral calls are generated at a node for one or more remote nodes, the remote 
nodes are notified when ACA referral is activated or deactivated. 
Busy Verification of Terminals and Trunks
DCS Busy Verification of Terminals and Trunks allows attendants and 
multiappearance voice-terminal users to make test calls to voice terminals and 
trunk groups that are located at other nodes in the DCS.
To use this feature, you must have a DCS Trunk Group between the local and 
remote switches, and the trunks in that trunk group cannot insert digits on 
incoming calls. If you need digit insertion on these trunks, it should be added on 
the outgoing trunk based on the dialed digits.
Multiappearance voice terminal users can busy-verify an adjunct at a remote 
location by pressing Verify and dialing the TAC of the tie trunk group to the 
remote node. Then they must press Verify a second time and dial the desired TAC 
and the trunk group member number to be verified. Verification of the trunk then 
continues as if the trunk is on the same node. 
						

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Call Coverage 
DCS Call Coverage provides DCS messaging required for calls to be covered on 
remote systems when there is a DCS signaling link (BX.25, PPP, or ISDN-PRI) 
for the trunk groups. Calls to an extension on one system are covered by 
extensions on remote systems that are administered as coverage points.
Figure 4 shows an example of DCS Call Coverage.
Figure 4. DCS Call Coverage
In Figure 4, calls to Station A can be covered first by Station B, then by Station C 
or D, and finally by the AUDIX on system A. Alternatively, calls could be 
covered by Station C, then Station B, then Station D, and so on.
If the called party answers after the call goes to coverage and the coverage point 
has answered, then the called party, calling party, and coverage point are all 
conferenced together.
If the called party answers and the coverage point has not answered, the call to the 
coverage point drops and the called party connects to the calling party.
Exceptions to DCS Call Coverage
DCS Call Coverage is similar to Call Coverage, with the following exceptions:
~Coverage Answer Groups across nodes are not supported.
~Under the following error conditions, a call follows the coverage point’s 
coverage path. 
1. Station A
2. System A - DEFINITY ECS
3. DCS Tie Trunk Groups
4. System B - DEFINITY ECS
5. Station C
6. Station B7. PGATE or PI Board
8. X.25 or ISDN PRI DCS Signaling 
Link
9. Hop or ISDN TSC Gateway
10. Station D 
11. AUDIX Voice Lines
12. AUDIX - x34000 
						

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~When the DCS link is down, call consult operates differently. If Station A calls 
Station B but the call covers to Station C, then Station C consults back to 
Station B and Station B receives the consult call on the next call appearance.
~DCS Call Coverage does not support Coverage Call Back from a remote node.
Additionally, in some DCS Call Coverage situations, call coverage operation may 
deviate, including: 
~A call to the principal redirects to the remote coverage point, which is 
unavailable. The coverage point is considered unavailable when:
•The coverage point is not a valid extension, QDN, or VDN.
•The coverage point is busy with no hunting, forwarded, or has send all 
calls activated, or activates send all calls after ringing.
•The coverage point has no staffed agents or an invalid vector.
When the coverage point is unavailable, the local system determines the 
availability status from a time-out or from a message from the remote system. 
When the local system discovers that the coverage point is unavailable, it tries 
the next coverage point. If the last coverage point is unavailable, the previous 
coverage point rings until it is answered or until the caller hangs up. If only 
one coverage point exists in the path and it is unavailable, the principal’s 
station rings until it is answered or until the caller hangs up.
~A call to the principal is forwarded and the forwarded-to extension is not 
available. In this case, the first coverage point in the principal’s path is tried. 
Note that the coverage does not follow the forwarded-to extension’s coverage 
path.
~A call to the principal redirects to the remote coverage point, which answers. 
Subsequently, the principal goes off hook. In this case, the local system 
bridges the principal onto the call between the calling party and coverage point 
creating a conference among the three. The principal receives the call on the 
same call appearance as the original call.Error Condition Action
DCS link not up.
or
DCS trunk is not available.
or
DCS Call Coverage feature 
is not activated on the 
remote system.The call is routed to the remote coverage 
point. If the call is answered, it is treated as 
Call Coverage Off Premises (also called 
Remote Call Coverage). If the call is 
redirected at the remote coverage point 
before the DCS SRI expires, the remote 
point’s path is followed. If the call is not 
answered within the DCS SRI time-out 
period, the next coverage point is tried with 
DCS Call Coverage from the local system.
All trunks to the remote 
system, DCS or otherwise, 
are busyThe next coverage point is tried with DCS 
Call Coverage from the local system. 
						

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~A call to the principal redirects to the remote coverage point. While the remote 
coverage point is ringing, the principal answers the call. In this case the call is 
not cut through to the coverage point. Instead, ringing and ringback is removed 
from the coverage point and the call is cut through to the principal.
Call Forwarding 
DCS Call Forwarding allows all calls to an extension to be forwarded to a selected 
extension in the DCS network or to an external (off-premises) number.
If the Call Forwarding and DCS Call Forwarding are both active, and if a call is 
forwarded between extensions on the same node, the Call Forwarding coverage 
path is used. If the nodes are different, the DCS Call Forwarding coverage path is 
used.
Voice-terminal users in the DCS can activate/deactivate this feature with a dial 
access code or with a Call Forwarding button. 
Note:Calls can be forwarded to a Vector Directory Number (VDN) 
anywhere in the DCS network. An attendant cannot 
activate/deactivate Call Forwarding for a VDN.
Call Waiting 
DCS Call Waiting allows calls from one node to busy single-line voice terminals 
at another node to wait until the called party is available to accept the call. With 
DCS Call Waiting, a single-line voice terminal user, by knowing a call is waiting, 
can quickly process calls from locations within the DCS. DCS Call Waiting 
functions the same as normal Call Waiting.
DCS Call Waiting includes the following features:
~Attendant Call Waiting
~Call Waiting — Termination
~Priority Calling
DCS priority calling from the attendant station is not available.
Distinctive Ringing 
DCS Distinctive Ringing activates the called-terminal alerting or ringing device to 
indicate the type of incoming call to the user before they answer it. Distinctive 
Alerting functions in a DCS environment the same as it does within a single 
system.
By default, internal calls are identified by a1-burst ringing pattern, external calls 
by a 2-burst ringing pattern, and priority calls by a 3-burst ringing pattern. 
However, you can administer these patterns.
Leave Word Calling 
LWC transparency in a DCS configuration allows messages from a DEFINITY 
switch to another node, depending on the storage capability of the remote node. 
						

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Multiappearance Conference/ Transfer 
DCS Multiappearance Conference/Transfer provides transparency for transferring 
calls and conferencing calls within a DCS network. A user in the DCS can initiate 
conference calls among or transfer calls originated from extensions in the DCS 
network to another extension within the DCS by dialing the UDP extension. (For 
transferred calls, the destination need not be within the DCS.)
In a DCS, if a party in a conference hangs up or completes a transfer leaving only 
outgoing trunks on the call, the system attempts to preserve the connection if any 
of the remaining parties on the call is a DCS tie trunk.
Trunk Group Busy/Warning
Indication
DCS Trunk Group Busy/Warning Indication provides attendants with a visual 
indication that the number of busy trunks in a remote group reached an 
administered level. A visual indication is also provided when all trunks in a trunk 
group are busy.
Note:DCS Trunk Group Busy/Warning Indication is not available if you 
are using DCS over ISDN-PRI.
To use this feature, you must have a DCS Trunk Group between the local and 
remote switches, and the trunks in that trunk group cannot insert digits on 
incoming calls. If you need digit insertion on these trunks, it should be added on 
the outgoing trunk based on the dialed digits.
Except for System 75, System 85, and DEFINITY G2 switches, you can 
administer DCS Trunk Group Busy/Warning Indication only for remote trunk 
groups that are directly connected to the local switch. Trunk group access codes 
for these trunk groups must be 3 digits or less and cannot include trunk members 
100 through 999.
DCS with Rerouting 
DCS with Rerouting allows a call’s connection between two DEFINITY systems 
to be replaced by a new connection. All of the trunks used in the original path 
must be DCS and the new path utilizes only DCS trunks. DCS with Rerouting 
provides the following capabilities:
~Attempts to obtain a better (generally less expensive) connection.
~May replace the current path of a call with a route that is better in terms of 
Automatic Alternate Routing/Automatic Route Selection (AAR/ARS) routing 
preferences administered on a DEFINITY ECS.
~Frees up resources being used unnecessarily.
DCS with Rerouting primarily provides you with the ability to attempt to be more 
effective with the usage of Trunk groups administered for Supplementary Services 
Protocol Option E (SSE) during the existence of an active call. This means using a 
more preferred route (in terms of UDP/AAR/ARS routing preferences 
administered on the PBX) between the PBXs involved.
Your users invoke DCS with Rerouting by Call Transfer, Transfer out of Audix, 
and dial 0 out of Audix. DCS with Rerouting must be enabled on a switch-wide 
basis and the trunk groups involved must be administered as SSE. 
						

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Interactions
•When interworking with non-ISDN trunks or non-Supplementary Service Option 
E ISDN trunks, DEFINITY acts as a gateway in the following sense:
~When a call is tandeming through a DEFINITY system from a non-ISDN 
trunk to an SSE trunk or from a non-Option E to an SSE trunk, the system acts 
as an incoming gateway.
~When a call is tandeming through a DEFINITY system from an SSE trunk to a 
non-ISDN trunk or from an SSE trunk to a non-Option E trunk, the system acts 
as an outgoing gateway.
As an example, when calls come in from the public network to the DCS 
network and then are transferred to another extension within the private 
network, DEFINITY functions as an incoming gateway and rerouting occurs.
•If a conference call is transferred, rerouting will not occur.
Italian DCS Protocol
Italian DCS Protocol (also known as Enhanced DCS) adds features to the existing 
DCS capabilities.EDCS is used primarily in Italy. EDCS adds the following 
features:
~Exchanging information to provide class of restriction (COR) checking 
between switches in the EDCS network
~Providing call-progress information for the attendant
~Allowing attendant intrusion between a main and a satellite
~Allowing a main PBX to provide DID/CO intercept treatment rather than the 
satellite PBX.
Note:EDCS is not compatible with DCS Over/Under ISDN-PRI. With 
EDCS, all nodes must use EDCS. If used with ISDN-PRI, 
configure the switch as a DCS node. Also, DCS-ISDN display 
enhancements are not currently available in EDCS.
How to administer 
Enhanced DCS
Form Field
Feature-Related System 
Parameters
•Enhanced DCS Enabled?
•Apply Intercept Locally?
•Enforce PNT-to-PNT Restrictions? 
						

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ISDN/X.25 gateway
DEFINITY ECS can serve as an interface between PBXs that support the D-channel 
signaling feature and those that do not support this feature. The switch providing this 
interface is known as the ISDN-DCS Gateway node and provides backward 
compatibility to existing traditional DCS networks.
It maintains a mapping between processor channels and Administered NCA-TSCs. 
When a DCS D-channel message arrives on an Administered NCA-TSC acting as a 
gateway, it is converted to a traditional DCS message and sent out through the 
processor channel that has been administered to map to this Administered NCA-TSC. 
Likewise, when a traditional DCS message arrives at the gateway node on a processor 
channel acting as a gateway, it is converted to a DCS D-channel message and sent out 
through the Administered NCA-TSC that has been associated with this processor 
channel on the ISDN Gateway Channel form.
In summary, a gateway is required whenever a transition is being made from BX.25 
signaling to D-channel signaling. When the transition takes place at a switch that sits 
between that part of the network that supports D-channel DCS and that part that does 
not, that switch is an ISDN-DCS Gateway. A DCS network consisting entirely of 
switches that support D-channel DCS never requires an ISDN-DCS Gateway because 
none of the switches require “translation” to/from BX.25.
DCS Over ISDN-PRI D-channel
DCS Over ISDN-PRI D-channel (DCS+) enhances DCS by allowing access to the 
public network for DCS connectivity between DCS switch nodes. With this feature, 
DCS features are no longer restricted to private facilities.
The ISDN-PRI B-channel is used for voice communications, and the ISDN-PRI 
D-channel transports DCS control information. DCS Over ISDN-PRI utilizes the 
Message-Associated User-to-User Information (MA-UUI) and Temporary Signaling 
Connections (TSC) to transport certain DCS control information. MA-UUI allows 
additional user-specific information to be transported along with certain ISDN 
call-control messages.
Note:Use this feature only over DS1/E1 or T1 circuit packs that are 
administered to Country Protocol Option 1, Protocol Version A 
(even in a private network environment) independent of what 
country the system is in.