3Com Nbx 100 And Ss3 Nbx Administration Guide

							Dial Plan Concepts and Overview31
Normally, you completely configure a dial plan before you start to use the 
system to control the telephones. Although you can make changes later, 
major changes in the dial plan can disrupt the system.
Decide whether you want to use a 3-digit or 4-digit dial plan before you 
create the dial plan, autodiscover, or manually add telephones or other 
devices to the NBX system.
When you import a dial plan, some parameters of the system change 
immediately. Others change only when you reboot the NBX system. 
3Com recommends that you reboot the NBX system each time that you 
change the dial plan.
Rebooting the system disrupts service to the telephones. Plan to reboot at 
a time that does not inconvenience telephone users.
Pretranslation
Pretranslation is the process of translating (or manipulating) dialed digits 
before they are passed to the appropriate dial plan table for subsequent 
routing. You can set the dial plan to perform pretranslation on incoming 
or outgoing calls:
For more information, see “Dial Plan Pretranslators”
 later in this chapter.
Routing
Routing specifies how a call reaches a destination. You define the routes 
for the system to use in the Routes section of the dial plan configuration 
file.
When you define call routing, you can also instruct the system to perform 
pretranslations (digit manipulations). Both destination routes and timed 
routes have digit manipulation operations (append, prepend, replace, 
stripLead, or stripTrail).
The system passes dialed digits first through the device’s Least Cost 
Routing table (if there is one). If the system finds no entry there, it then 
uses the Normal dial plan table. If it does find an entry in the Least Cost 
Routing table, it attempts to use that entry and, even if the attempt is 
unsuccessful, it does not use the Normal table.
You can route incoming calls to the Auto Attendant port, and you can 
instruct the Auto Attendant to route these calls to any internal or external 
number. 
						

							32CHAPTER 2: DIAL PLAN
CAUTION: If you configure the Auto Attendant so that it can access any 
external number, you risk the possibility of toll fraud. You can reduce the 
possibility of toll fraud by explicitly putting specific external numbers into 
the outgoing dial plan table. This precaution prevents outside callers from 
dialing any external number except the ones that you define.
There are two types of routes:
■Destination routes — Specify the extension of a destination device. 
They can also perform digit manipulation operations on the dialed 
digits that resulted in the selection of this route before those digits are 
dialed on the destination device.
■Timed routes — Specify time of day and day of week criteria which, 
when met, result in a particular destination route being selected.
CAUTION: If you operate the NBX system in Keyset Mode, routes are not 
applicable.
For more information, see “DestinationRoute Create”
 and “TimedRoute 
Create” and related entries under “Dial Plan Configuration File 
Commands” later in this chapter.
System Features
Affected by the Dial
Plan ConfigurationThe dial plan configuration affects several system features:
■Keyset Mode Operation Using the Dial Plan
■Hybrid Mode Operation Using the Dial Plan
■Off-Site Notification
Keyset Mode Operation Using the Dial Plan
If you map any telephone buttons that have LEDs to specific Analog Line 
Card ports, you enable Keyset mode in the NBX system. Instead of dialing 
a single digit (typically 8, 9, or 0) before placing an outside call, the user 
presses a button to select an available Analog Line Card port. The user 
defines the routing (that is, the selection of a destination device) by 
pressing the button to select the Analog Line Card port; however the NBX 
system controls the call using the dial plan.
You cannot map a digital line extension in Keyset mode.
The NBX system applies any Class of Service restrictions that are 
associated with the users telephone to determine whether to make a 
call. The system also uses any pretranslator that a device uses and 
performs any required digit manipulation operations before it actually 
transmits the digits on the Analog Line Card or Digital Line Card port. 
						

							Dial Plan Concepts and Overview33
Hybrid Mode Operation Using the Dial Plan
If you map telephone buttons for some telephones but not others, you 
enable Hybrid mode (a mixture of standard and Keyset behaviors). The 
system provides a system-wide External Prefix setting, which allows the 
administrator to establish a prefix.
Off-Site Notification
The NBX system uses off-site notification to notify users when new voice 
mail messages arrive. You can define notification devices and assign them 
in the Internal dial plan as well as through the NBX NetSet utility.
Example: When voice mail arrives, the NBX system dials the telephone 
number of the user’s pager.
Typically, you use a system-wide prefix to designate which device or 
devices you want to use for outdialing purposes, including off-site 
notification calls.
Example: If the user’s pager number is 800-555-3751, and the 
system-wide prefix digit is 9, the system dials 98005553751 to send 
a call to the user’s pager.
To tell the system to dial a single Line Card port or a restricted number of 
Line Card ports, create a suitable pool of Line Card ports for that purpose, 
and then use an existing set of dial plan table entries (such as the entries 
that begin with 8) or create a new set of entries to allow the dial plan 
devices to route calls via the selected line card ports.
Example: You set up one 4-port card to handle all off-site notification calls. 
You create a set of entries in the Internal dial plan table that each start 
with the digit 8. You define a route to the 4-port card for all of these dial 
plan entries so that whenever the system acts on one of these entries, it 
uses one of the 4 ports on that card to dial out and notify the user.
To apply different off-site CoS restrictions to different users, you need 
multiple dial plan entries. If you are not trying to apply the CoS 
restrictions, then a single dial plan entry is sufficient. 
						

							34CHAPTER 2: DIAL PLAN
Dial Plan TablesDial plan tables contain information that controls how the system routes 
calls. Each dial plan configuration file consists of at least three dial plan 
tables. This section discusses these topics:
■Dial Plan Command Format
■Internal Dial Plan Table — Must be table ID 1
■Incoming Dial Plan Table — Must be table ID 2
■Least Cost Routing Dial Plan Table — Must be table ID 3
■Adding New Dial Plan Tables
CAUTION:Tables 1, 2, and 3 must exist. Do not delete them. You may 
create additional dial plan tables if necessary, but they must be numbered 
4 or higher.
If the Least Cost Routing table exists, it takes precedence over the Internal 
table. If the system cannot find a Least Cost Routing table, it attempts to 
find a corresponding entry in the Internal table. If you have entries for the 
same purpose in both the Least Cost and Internal tables, the behavior of 
the dial plan can be confusing.
See “Dial Plan Command Format”
 next for a description of dial plan 
command syntax and structure. 
For a complete list and description of dial plan commands, including 
command arguments and examples, see “Dial Plan Configuration File 
Commands” later in this chapter.
Dial Plan Command
FormatEach dial plan table contains a sequence of commands. These commands 
collectively determine how calls are handled.
Most of the dial plan commands have a very similar format, as shown in 
Figure 2
. 
						

							Dial Plan Tables35
Figure 2   Dial Plan Command Format
Ta b l e 6 describes each field of a dial plan command.
Table Create 1 Internal
/                  Id Entry  Digits       Min Max   Class          Prio Route
/
TableEntry Create   1     1  0              1   1   Internal          0     4
TableEntry Create   1     2  1              3   3   Internal          0     0
TableEntry Create   1     3  2              3   3   Internal          0     0
Table Create 2 Incoming
/                  Id Entry  Digits       Min Max   Class          Prio Route
/
TableEntry Create   2     1  0              1   1   Internal          0     4
TableEntry Create   2     2  1              3   3   Internal          0     0
Table Create 3 Least Cost Routing
/                  Id Entry  Digits       Min Max   Class          Prio Route
TableEntry Create   3     1  91607387      12  12   LongDistance     0     10
Command
Table ID Number
Leading Digits to Collect
Table Entry ID Number
Call Classification — Used
with Class of Service
Priority
(Not Used)
Ta b l e  N a m e
Number of the 
route (dial tone 
facility) from 
Routing Tables
Maximum and Minimum
Characters to Collect
Ta b l e 6    Dial Plan Command Fields
FieldDescription
CommandCommand name. For example, TableEntry Create is the command that make Class of Service 
and call routing decisions based on the correspondence of dialed digits and table entry digits. 
See “Dial Plan Configuration File Commands”
 later in this chapter for a description of each 
command.
Table ID NumberTable ID number. This is always 1 for the Internal dial plan table, 2 for the Incoming dial plan 
table, and 3 for the Least Cost Routing Table. 
						

							36CHAPTER 2: DIAL PLAN
If a new entry in the Internal table appears not to work, it is possible that 
the system is using an entry from the Least Cost table instead. To avoid 
such conflicts, you can accomplish least cost routing using only the 
Internal table. 3Com strongly recommends that, to keep the dial plan as 
simple as possible, you use only the Internal table for least cost routing.
For more information on how to use the dial plan configuration file, 
see “Managing the Dial Plan Configuration File”
 later in this chapter.
Basic Dial Plan Table Examples
These examples describe the basic operation of a dial plan table. 
Example: If you are using a 4-digit dial plan and the telephone 
extensions start with 2, then the table entry with 2 in the Digits column 
typically has 4 in the Min column. Before making a decision, the system 
would collect all 4 digits of the extension. If the caller dials fewer than the 
Min number of digits, the system times out in 20 seconds. 
Table Entry ID 
NumberTable entry number (a unique number for each entry in the table). These numbers are usually 
in ascending order in the table, but you can change the order. For example, you might want 
to place a new item near other items of the same type (that begin with the same digit) in 
order to help you when you troubleshoot the configuration file.
DigitsOne or more digits that begin the dial sequence. Either single or multiple entries can start 
with the same digit. The system uses this field in conjunction with Min and Max to determine 
when to make the call routing decision.
Most sample tables have a single entry for digit 0 (zero) to specify how the system handles a 
telephone number which has zero as the first digit.
If you want the system to handle calls differently, depending on whether they start with 90 
or 91, you must have one entry in the table for each of these 2-digit sequences.
MinMinimum number of digits that the system collects before routing the call.
MaxMaximum number of digits the system collects before routing a call.
ClassClass of Service (CoS). The system uses this information to decide whether a caller is allowed 
to make this specific type of call. The possible classifications are:
Internal, Local, LongDistance, International, WAN, Toll- Free, Emergency, COCode, 
Wireless, Toll, Operator, AlternateLong, TrunkToTrunk, Diagnostics, NotAllowed, Other
Each of these values corresponds to a selection in the NBX NetSet utility.
PriorityPriority number. This field is not used at this time, but must be present and should always be 
0 (zero).
RouteRoute number. This identifies an entry in the Routes section of the dial plan. Zero is a typical 
value for internal calls, and indicates that this call uses no route, in which case, digits are 
transmitted as soon as they are dialed.
Ta b l e 6    Dial Plan Command Fields (continued)
FieldDescription 
						

							Dial Plan Tables37
Example: If Digits = 2, Min = 4, and Max = 4, the system knows that if 
the first digit is 2, it must collect no less than 4 and no more than 4 digits 
before making the call routing decision.
If the caller dials at least the minimum number of digits and not more 
than the maximum number of digits, the system waits 5 seconds and 
then routes the call based on the digits dialed.If the caller dials more than 
the maximum number of digits, the system attempts to place the call.
Often, Max value and the Min value are identical, because you want the 
system to collect a specific number of digits, no more and no less.
Example: For internal extensions, you want the system to collect exactly 
3 digits (4 in a 4-digit dial plan) before making a decision, so you would 
set both Min and Max to 3 (4 in a 4-digit dial plan).
The two columns may be different if the table entry applies to more than 
one situation.
Example: In the United States, the Min value for the 90 entry is 2, 
because 90 allows an internal caller to reach a telephone company 
operator (9 to get an outside line, and then 0 to get the operator). The 
Max value is 64, because the caller can continue to dial after the zero, 
entering a number to call, plus a telephone credit card number, and 
possibly an identification code number.
If the caller dials only 90 (which satisfies the minimum of two digits) and 
stops dialing, the system waits for 5 seconds. If no other digits are 
entered, the system connects the caller to the operator.
If other digits are dialed, the system accepts them up to the limit of 64. If 
the caller stops after dialing fewer than 64 digits, the system again waits 
5 seconds before acting on the dialed sequence of digits.
Example: You can assign a new employee to the Default User Group. 
You can then set the permissions for that group so that group members 
have permission to make LongDistance calls when the system mode is 
Open or Lunch, but not when the system mode is Closed or Other.
Example: You can assign the company’s Vice President of Finance to a 
group that you name the All Privileges Group. You can set the 
permissions for that group so that group members have permission to 
make LongDistance calls during all system modes. 
						

							38CHAPTER 2: DIAL PLAN
Internal Dial
Plan TableThe Internal dial plan table (table ID 1) defines how to handle calls placed 
from internal devices, such as NBX Business or Basic Telephones, to a 
destination. A destination can be another internal device, such as a local 
telephone, or an external telephone line (Analog Line Card or Digital Line 
Card) that connects the NBX system to other facilities.
The Internal dial plan table consists of a series of commands. For an 
example of the command format, see “Dial Plan Command Format”
 
earlier in this chapter. Table 6
 earlier in this chapter describes each 
element of the command. Table 7
 describes the predefined routes.
You cannot delete or modify predefined routes, only create new routes.
Each device must have a Normal table. The Least Cost Routing table is 
optional. Telephones use the Internal dial plan table (table ID 1) as their 
normal outbound table and the Least Cost Routing table (table ID 3) as 
their long distance routing table.
Incoming Dial
Plan TableThe Incoming dial plan table (table ID 2) defines how calls arriving from 
outside the NBX system are routed to extensions. Incoming calls can 
arrive on analog telephone lines or through Digital Line Card ports.
The incoming dial plan table consists of a series of commands. For an 
example and basic understanding of the command format, see “Dial Plan 
Command Format” later in this chapter. For a description of the each 
element of a dial plan command, see Table 6
 earlier in this chapter.
By default, Line Card ports, Digital Line Card ports, and H.323 gateways 
use the Incoming dial plan table as their normal dial plan table. An 
Incoming dial plan table typically has a more restricted list of dialable 
digits than the Internal dial plan table. You usually cannot dial extensions 
associated with internal paging or Analog or Digital Line Card ports.
Ta b l e 7    Predefined Routes
Route NumberDescription
1Local CO (strip)
2Local CO (no strip)
3Voice Application (Auto Attendant on extension 500)
4Attendant (person)
5H.323 Gateway
6Least Cost Route example
OtherUser-defined routes 
						

							Dial Plan Tables39
Least Cost Routing
Dial Plan TableThe Least Cost Routing table (table ID 3) defines how to route calls in 
order to minimize the cost of those calls.
Example: You might use two different long distance carriers, one for a 
specific geographic region, and one for all other areas of the country. In 
the Least Cost Routing table, you can create entries that route calls 
differently for those two geographic areas. Each country uses a different 
method to accomplish this. In the United States, you can specify the area 
codes that apply to a geographic region. In France, you can specify a 
carrier by adding prefix digits to the telephone number.
By default, internal telephones specify the Least Cost Routing table as 
their least cost table. Typically, devices associated with the Incoming dial 
plan table (Line Card ports, Digital Line Card ports, and H.323 gateways) 
do not use the Least Cost Routing table.
The Least Cost Routing table is optional. If it does not exist, the system 
uses the Internal table routing destinations. If you have entries in both the 
Least Cost and Internal tables for the same purpose, the behavior of the 
dial plan can be confusing. Therefore, 3Com recommends that you 
accomplish least cost routing using Internal Table entries. See TimedRoute 
Create, TimedRouteEntry Create, and TimedRouteOperation Create.
Example: If a new entry in the Internal table appears not to work, it is 
possible that the system is using an entry from the Least Cost table 
instead. To avoid such conflicts, accomplish least cost routing using only 
the Internal table. 3Com strongly recommends that you keep the dial 
plan as simple as possible by using only the Internal table.
Adding New
Dial Plan TablesIf you are sharing the system with another company or group and want 
to control calls differently at the two sites, you can add a fourth table.
Example: You assign one extension range to Company A and a different 
range to Company B. The fourth table controls the extension range for 
Company B, so that outbound calls from Company B’s extensions use 
only their external telephone lines.
You might also need a fourth table if a single company had two sites but 
only one NBX system. In order to properly route emergency (911) calls, 
you use the fourth table to define which extensions use each dedicated 
911 telephone line. 
						

							40CHAPTER 2: DIAL PLAN
Example: Users at site A dial 911 and the system uses the Internal table 
(table ID 1) to make the emergency call on one external telephone line. 
Users at site B dial 911 and the system uses table ID 4 to make the 
emergency call on a different external telephone line. The emergency 
staff know, based on the dialing number, which site has the emergency.
Enhanced 911, E911, is available in some areas. This service enables 
emergency staff to identify the specific location of the emergency. For 
example, in a campus of buildings, the emergency staff can identify the 
specific building, floor, and location from which the emergency call 
originated. The NBX system supports E911 over ISDN. The administrator 
must define an outbound call pretranslator to provide the specific 
extension number from which the 911 call originated.
Dial Plan 
PretranslatorsThe system uses pretranslators to modify digit sequences of incoming or 
outgoing calls. On incoming calls, pretranslators can map the entire 
dialed number (including area code) to an internal extension number. 
For example, an external party dials 978-555-0101 to reach the person 
on extension 101. Pretranslators ensure that the proper digits are 
mapped to the correct extension number.
For more information, see:
■Pretranslators for Incoming Calls
■Pretranslators for Certain Outgoing Calls
A typical pretranslator function involves mapping incoming DDI/DID 
telephone calls to internal extension numbers.
Example: Say that the DDI/DID telephone numbers range from 
508-555-4200 through 508-555-4299. The telephone company sends 
you the last 4 digits of the total telephone number. Internally, you want 
to use extensions 2000 through 2099. You can define a pretranslator to:
■Remove (stripLead) the first two digits of the incoming 4-digit 
sequence.
■Add (prepend) the digits 20 in front of the remaining 2 digits.
See “Managing Dial Plan Pretranslators”
 later in this chapter for detailed 
information and examples on creating and managing dial plan 
pretranslators.