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

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How to administer DCS 
Over ISDN-PRI 
D-channel
Note:There are several differences in administration between switches. 
For example, PRI is translated a little differently in G3r when 
traditional DCS and this feature are used in combination. On 
systems with AUDIX in a DCS environment, an additional column 
has been added to the Signaling Group form so you can specify 
which AUDIX and switch to use. When traditional DCS and DCS 
over ISDN are used in combination, translations are also different. 
Detailed descriptionA TSC provides a temporary signaling path through ISDN switches for exchanging 
supplementary service information on ISDN-PRI D-channels. There is no B-channel 
related to the connection; no data or voice transmissions take place. 
There are two types of temporary signaling connections:
•Call Associated (CA-TSC)
•Non-Call Associated (NCA-TSC)
CA-TSC
A CA-TSC refers to a service for exchanging USER INFORMATION messages 
associated with an ISDN B-channel connection by the call reference value of the call 
control data packets. On DEFINITY ECS, this type of TSC is used only for DCS 
features on ISDN-PRI Signaling Groups administered with Supplementary Service 
Protocol a.Form Field
Signaling Group 
•Max number of NCA TSC
•Max number of CA TSC
•Trunk Group for NCA TSC
•Administered NCA TSC Assignment 
fields
•Service/Feature
•Inactivity Time-out (min)
ISDN TSC Gateway 
Channel Assignments
•All
Trunk Group 
(ISDN-PRI)
•Used for DCS Node Number DCS 
Signaling
•NCA TSC Trunk Member
Route Pattern
•TSC
•CA TSC Request
Processor Channel 
Assignment
•Application
Feature-Related System 
Parameters
•Record TSCs for CDR 
						

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NCA-TSC
An NCA-TSC is a connection not related with any ISDN B-channel connections. 
DECINITY ECS supports two types of NCA-TSC that conform to two different 
protocol standards:
•The QSIG type of NCA-TSC is used for certain QSIG features such as Call 
Completion (Automatic Call Back). This type of NCA-TSC is referred to in the 
QSIG protocol standards as a Call-Independent Signaling Connection (CISC). 
Only ISDN-PRI Signaling Groups administered with Supplementary Service 
Protocol b support QSIG NCA-TSCs. For further information, see NCA-TSC  
(page 370).
•The AT&T type of NCA-TSC is used for the DCS Over ISDN-PRI D-channel and 
DCS AUDIX applications. Only ISDN-PRI Signaling Groups administered with 
Supplementary Service Protocol a support AT&T NCA-TSCs.
An AT&T NCA-TSC is an administered virtual connection established for 
exchanging USER INFORMATION messages on the ISDN D-channel. Once an 
AT&T NCA-TSC has been administered and enabled, it is active for an extended 
period of time. There are two types of administered NCA-TSCs depending on 
their setup mechanism: 
~Permanent (can be established by Near-end or Far-end) 
~As-needed
Once enabled, a permanent NCA-TSC remains established while the system is 
running. If the permanent NCA-TSC drops for any reason, the system attempts to 
reestablish the connection. An as-needed administered NCA-TSC is established 
based on user request and the availability of TSC facilities. The connection drops 
after an administered period of inactivity.
The system can transport DCS or DCS AUDIX messages over an ISDN-PRI 
D-channel and over BX.25 data links when functioning as a gateway between a 
switch equipped with DCS Over ISDN-PRI D-channel and a switch equipped with 
traditional DCS using BX.25 data links. In this situation, the messages travel from 
the gateway through the NCA-TSCs or CA-TSCs to TSC-capable switches and 
from the gateway to switches that support only traditional DCS via a BX.25 
logical channel.
At least one switch must be configured as an ISDN DCS Gateway node in a DCS 
network that consists of switches that support DCS Over ISDN-PRI D-channel 
and PBXs that do not support the feature. Switches directly connected to AUDIX 
serve as Gateway nodes. 
						

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DCS feature considerations
Attendant•If you call an attendant on another switch in the DCS network, your display shows 
the attendant’s name, but does not show the attendant’s extension, instead you see 
a zero where the extension should be.
Alphanumeric Display 
considerations•On outgoing DCS calls, display of the called name may be delayed for a few 
seconds until the required information arrives from the distant node. The called 
name display only works between DEFINITY ECS, DEFINITY Generic 1 and 
Generic 3 Systems, and System 75s.
Attendant Control of 
Trunk Group Access 
considerations•This feature is not available for trunk groups with 4-digit trunk access codes or for 
trunk members 100 through 999.
•If the remote node (where the trunk group to be controlled resides) is a System 75, 
Generic 1, or Generic 3, it is not necessary for that node to have an attendant 
console with corresponding three-lamp Trunk Hundreds Select button. However, 
if the remote node is a System 85, Generic 2.1, or Enhanced DIMENSION PBX, 
control of the trunk group is not allowed unless an attendant at that node has a 
corresponding three-lamp Trunk Group Select button.
•The attendant must use the Remote Trunk Hundreds Select button to directly 
access the controlled remote trunk group. If an attendant controls a remote trunk 
group, and that attendant dials the trunk access codes of the DCS tie trunk and the 
controlled remote trunk group, the call is routed to the attendant at the node where 
the trunk group resides.
•If Attendant Control of Trunk Group Access is activated, and no attendant is 
assigned, or the attendant is later removed, calls to a controlled trunk group route 
to the attendant queue.
Attendant Direct Trunk 
Group Selection 
considerations•This feature is not available for trunk groups with 4-digit trunk access codes or for 
trunk members 100 through 999.
Attendant Display 
considerations•CORs for a DEFINITY switch may not correspond to those used by an Enhanced 
DIMENSION PBX, System 85, or DEFINITY system Generic 2.1. Therefore, if 
the DCS network contains nodes other than Generic 1 or Generic 3, the display 
CORs may be misinterpreted. If it is important that certain CORs between various 
systems correspond with each other, those CORs should be administered 
accordingly.
•On outgoing calls, the display of called party information may be delayed a few 
seconds until the required information arrives from the remote node. The called 
party information is displayed only if both nodes are Generic 1 or System 75.
•DCS tie trunks between nodes must be administered with the Outgoing Display 
enabled. This enables the called party’s name to be displayed at the calling 
attendant’s display.
Automatic Callback 
considerations•An Automatic Callback request is canceled automatically if the called party does 
not become available within 40 minutes, or if the calling party does not hang up 
within six seconds after activating Automatic Callback. 
						

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DCS Over ISDN-PRI 
D-channel 
considerations•The gateway node serves as the terminating node to the D-channel DCS network 
as well as the terminating node to the traditional DCS network.
A PBX serving as an ISDN DCS Gateway node introduces some interesting 
situations when administering processor channels in an associated traditional DCS 
PBX. In a traditional DCS network, (BX.25 processor channel links) Remote 
Port in the “Processor Channel Assignments” form refers to the processor 
channel of the destination PBX. In an Integrated DCS network, Remote Proc 
Chan in the “Processor Channel Assignments” form refers to the processor 
channel of the Gateway PBX (if the destination PBX is an ISDN DCS PBX), not 
the destination PBX.
On the contrary, Machine-ID in the “Processor Channel Assignments” form 
refers to the destination PBX, either an ISDN DCS PBX or a traditional DCS 
PBX. The Gateway PBX number 
must not be used in this field if the destination 
PBX is an ISDN DCS PBX.
Enhanced DCS 
considerations•If the DCS link fails, the administrator can choose to allow calls to continue 
without class of restriction checking or to block all DCS calls to inward-restricted 
stations.
LWC considerations •LWC cannot be successfully activated toward any system that is not capable of 
storing the messages, either internally or in an associated adjunct.
•Messages from one node, through an intermediate node, to a remote node do not 
require storage capability at the intermediate node.
•LWC transparency is supported for all DCS configurations except for cases when 
either the activating node or the remote node is either an ENHANCED 
DIMENSION PBX or a System 85 R2V1.
•Retrieval of LWC messages is permitted only from a terminal at the node where 
the messages are stored.
•DCS LWC cannot be activated from an attendant console.
Trunk Group 
Busy/Warning 
Indication 
considerations•Trunk Group Busy and Trunk Group Warning Indication is particularly useful 
with the Attendant Control of Trunk Group Access feature. The indicators alert 
the attendant when control of access to local and remote trunk groups is necessary. 
						

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DCS Interactions
Alphanumeric Display The following features allow transparency with respect to Calling or Called Name 
Display and miscellaneous ID. 
•Call Coverage
At the calling terminal, the miscellaneous id “cover” is not displayed.
•Call Forwarding
When a system user calls a party on a different node in the DCS and the call is 
forwarded, the miscellaneous ID “forward” is not displayed. At the covering 
(forwarded-to) user’s terminal, only the calling party’s name is shown; the called 
party’s name is not displayed.
•Call Park
When a DCS call between a local system user and a user on another node is 
parked by the remote user, the miscellaneous ID “park” is not displayed at the 
local terminal.
•Call Pickup
When a DCS call from a system user to another node is answered by way of Call 
Pickup, the miscellaneous ID “cover” is not displayed at the caller’s terminal.
•Call Waiting
When a DCS call from a system user to another node is waiting at the called 
terminal, the miscellaneous ID “wait” is not displayed at the caller’s terminal.
•CAS 
When a user dials the extension for CAS, a RLT is seized or the caller is queued 
for an RLT. The caller’s terminal displays the trunk group identifier, such as 
OPERATOR.
•ISDN-PRI
If both DCS and ISDN-PRI features are provided with a system, the ISDN-PRI 
display information displays in DCS format.
DCS Attendant Control 
of Trunk Group Access •DCS Attendant Display
When a user attempts to access a controlled trunk group and is routed to the local 
attendant, the display shows the reason the call was redirected. If the call is routed 
via CAS or the Inter-PBX Attendant Calls feature, the display does not show the 
reason the call was redirected.
•UDP 
DCS tie trunks should not be attendant controlled. This would result in all UDP 
calls on the controlled tie trunk being routed to the controlling attendant instead of 
to the desired destination. 
						

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Attendant Display •When both ISDN and DCS display information, or only DCS display information, 
is received, the switch displays the DCS display information in the DCS format. If 
ISDN display information is received, and no DCS display information is 
received, then the ISDN display information displays in the ISDN formats.
Automatic Callback  •Attendant Control of Trunk Group Access and DCS Attendant Control of Trunk 
Group Access
Automatic Callback cannot be activated if the call uses a controlled trunk group.
Busy Verification  •If the Trunk Identification by Attendant feature is used during busy verification of 
a trunk (Trunk ID button is pressed), the trunk access code and trunk group 
member number of the DCS tie trunk being used is displayed.
•DCS Busy Verification of Terminals and Trunks transparency is lost if the routing 
pattern is administered to not delete the RNX and the AAR prefix is inserted on 
the terminating switch trunk group. The voice terminal display at the terminating 
switch displays only a=station name. Extension is left blank.
Call Coverage DCS Call Coverage has the same interactions as Call Coverage plus the following 
additional interactions.
•Call Coverage Off Premises
If the coverage point is a non-UDP number in the remote call coverage table, Call 
Coverage Off Premises is applied to the call rather than DCS Call Coverage, even 
if a DCS link exists to the remote system.
•Coverage Answer Groups
DCS Call Coverage to Coverage Answer Groups on remote systems are not 
supported by DCS Call Coverage. Coverage answer groups cannot be 
administered on a system other than the principal’s system.
•Coverage Call Back
DCS Call Coverage does not support Coverage Call Back from a remote node. 
•Displays
The displays on the DCS Call Coverage point’s terminal may be different than 
those associated with the Call Coverage feature in the following situations:
~When the call from the calling party to the principal or the redirected call to 
the coverage point travel over ISDN-PRI trunk groups.
~When the calling party is on a System 85 or Generic 2.
~When the DCS name message is not received by the remote (coverage point’s) 
system.
•Go to Cover
Go to Cover is not supported over DCS and therefore is not supported with DCS 
Call Coverage. 
						

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•Leave Word Calling Back to Principal
With DCS Call Coverage, a covering user on a different node cannot press their 
LWC button to leave a message for the principal to call the covering user.
•Queuing
DCS Call Coverage interacts with queuing in the following way. If a call is 
queued to a coverage point, such as a queue to a hunt group or an ACD split, and 
the queue is not full, the call remains in the queue without subsequent redirection 
until answered or until the caller hangs up.
Call Forwarding  •If the forwarding extension and the designated extension are at different nodes, 
and the designated extension’s coverage criteria are met on a forwarded call, the 
call is redirected to a point in the designated extension’s coverage path.
•If the forwarding extension and the designated extension are at different nodes, 
LWC and Coverage Callback cannot be activated at the designated extension for a 
forwarded call.
•There is a 30-second interval during which calls forwarded from the DEFINITY 
switch to another DCS node is denied. This prevents forwarded incoming trunk 
calls from being forwarded ad infinitum between two extensions.
Call Waiting  •DCS Call Waiting is denied when the following features are activated at the 
single-line voice terminal:
~Automatic Callback (to or from the voice terminal)
~Data Privacy
~Data Restriction
•On incoming trunk calls to the attendant extended over DCS trunks, Attendant 
Call Waiting interacts with the EDCS feature.
DCS Over ISDN-PRI 
D-channel•ASAI
For incoming calls on DCS over ISDN-PRI, ASAI applications receive the 
ISDN-PRI Calling Party Information, not the DCS Calling Party Information.
•Attendant DXS with Busy Lamp Field
An attempt by the attendant to directly select an extension that has been 
previously administered as belonging to a administered NCA-TSC results in 
intercept tone being received.
•CDR
CDR records both the status and the utilization of TSCs. Both CA-TSCs and 
NCA-TSCs can be recorded. For more information, consult the CDR description 
in this manual or the CDR manual. 
						

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•D-channel Backup
In the event of a D-channel switchover (primary to secondary or secondary back 
to primary) in a private network, administered NCA-TSCs that were active are 
assumed to have remained active. Any unacknowledged user-user service requests 
are assumed to be rejected, and administered NCA-TSCs which were in the 
process of being established at the time of the switchover are dropped when the 
switchover occurs. Those administered NCA-TSCs that were dropped are 
reattempted again.
If a D-channel switchover occurs on a D-channel going to the public network then 
all TSCs are dropped. A maintenance-provided “heartbeat” message periodically 
is sent over each permanent administered NCA-TSC to ensure that such a 
situation is detected and recovered from.
•Distributed Communications System AUDIX (DCS AUDIX)
The DCS over ISDN-PRI D-channel feature can be used to support DCS AUDIX. 
(The connection between G3si and AUDIX should be BX.25.)
•GRS
GRS selects TSC compatible facilities when routing NCA-TSCs. In other words, a 
NCA-TSC request can only select a routing preference that supports TSCs.
In a tandem node, GRS first selects facilities that support TSCs if the call falls into 
any one of the following two conditions:
~It requests a CA-TSC explicitly
~It contains a DCS information element in the SETUP message
Once a trunk group with available members is selected, the call proceeds even if 
all the TSCs belonging to the associated signaling group are active. In other 
words, the completion of a call is given priority over DCS transparency.
•SDN
The DCS over ISDN-PRI D-channel feature allows the system to access public 
networks such as SDN. SDN supports all DCS features except for the following:
~DCS Attendant Control of Trunk Group Access
~DCS Attendant Direct Trunk Group Selection
~DCS Busy Verification of Terminals and Trunks
•Voice Terminals
An attempt to dial an extension that has been previously administered as 
belonging to an administered NCA-TSC results in intercept tone being received.
Distinctive Ringing •Distinctive Ringing
Distinctive Ringing treats a call from another switch in a DCS arrangement as 
external; DCS Distinctive Ringing treats such calls as internal. If both features are 
administered, DCS Distinctive Ringing takes precedence. If EDCS is activated, 
DID treatment may be different. See Example DCS configurations  (page 329). 
						

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Enhanced DCS •Class of Restriction
When a call goes to coverage, it is the called party’s (not the covering party’s) 
restrictions that are used.
LWC•DCS Multi-appearance Conference/Transfer
Activation of LWC is denied after a DCS call has been conferenced or transferred.
Multiappearance 
Conference/Transfer•Voice Terminal Display
No display transparency is provided for DCS Multi-Appearance 
Conference/Transfer.
•EDCS
On calls to or from Public Network Trunks, calling/called party restrictions are 
checked when EDCS is active.
Trunk Group 
Busy/Warning 
Indication•Loudspeaker Paging Access
If Trunk Hundreds Select buttons are assigned for Loudspeaker Paging Access 
zones, Trunk Group Busy Indicators provide a visual indication of the busy or idle 
status of the zones at the remote location as well as at the local node.
Example DCS configurations
The following two examples provide details for setting up two basic DCS networks. 
The first is a two-node network and the second is a three-node network. These 
examples use BX.25 and D-Channel signaling connections. For examples of TCP/IP 
signaling for DCS, see Chapters 2 and 3 in this book.
2-Node private network 
with AUDIXFigure 5 shows a 2-node DCS/AUDIX D-channel network. In this configuration, 
DCS feature transparency is achieved exclusively through the exchange of 
user-to-user information on the D-channel using one of the three methods discussed 
earlier — MA-UUI, CA-TSCs or NCA-TSCs. Although NCA-TSCs are nothing 
more than virtual connections on the D-channel, they are shown as independent 
entities in the diagram for the purposes of clarity. Administered TSC 2/1 (that is, the 
first Administered NCA-TSC of signaling group 2) of Switch A is connected to TSC 
4/1 of Switch B. This virtual connection is used in the exchange of user-to-user 
information for DCS features not associated with any current B-channel connection.
Notice that for AUDIX, a BX.25 data link is no longer required between the host 
switch and the remote switch(es). AUDIX messages between the AUDIX and the 
remote switch will use the AUDIX Gateway functionality of the host switch and will 
be transported to the remote switch via an NCA-TSC. Specifically, AUDIX messages 
destined for Switch B will arrive at Switch A on Link 1, Channel 2 (processor channel 
57), be converted to ISDN-PRI Q.931 format and sent out via Administered 
NCA-TSC 2/2.
This is accomplished by administering processor channel 57 as a gateway and 
mapping it on the gateway form to Administered NCA-TSC 2 of signaling group 2 
that is also administered as a gateway. 
						

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Figure 5. 2-Node private network
The following tables show you how you would complete each of the necessary forms.
AUDIX administration
•
AUDIX Translations form
Administration for switch 1
•
Dial Plan form
•Uniform Dial Plan form
•AAR Digit Conversion form
•AAR Analysis Table
1/1 1  Link Link
TSC TSC 1
SWITCH 2SWITCH 1 AUDIX
. . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D-CHANNEL
BX.25
1/2
1/2 1/1G3i
PBX ID 2
RNX 222 G3i
PBX ID 1
RNX 221
AUDIX 2DCS 1-2
AUDIX 2 AUDIX 1
4/1
4/21
2/2 2/12
Switch 
NumberAUDIX 
PortSwitch 
Port*
* Switch Port refers to the processor channel that is used for AUDIX in the
PBX.
Logical 
ChannelData 
Link
115911
225721
Start Dig. Len Usage
44ext
54ext
Ext Code Type Location Code
5xxx UDPcode 222
Matching 
PatternMin Max Del Replacement 
StringNet Conv
221 773- extn
Dialed String Min Max Rte Pat Call Type Node Num
222 7 7 2 aar 2