Primary Rate Interface (PRI) and T1 Feature

Description

Incoming Calls

Incoming calls are routed by line appearance or can apply routing by dial plan, a routing system for incoming calls programmed by the Dial Plan Routing Table (see Sample PRI Dial Plan Routing Table).

 

Where the Switch Type setting is LEGEND-Ntwk or LEGEND-PBX for a PRI trunk, incoming calls are automatically set to Route Directly to UDP. PRI routing by dial plan and line appearance are not used. This cannot be changed unless the Switch Type setting is modified.

PRI Call Processing (Non-Tandem Only)

 

 

Where:

 

 

ARS = Automatic Route Selection

DPR = Dial Plan Routing Table

NS = Network Selection Table

CBC = Call-by-Call Services Table

DPT = Direct Pool Termination

SA = System Access

PL = Personal Line

 

SSS = Special Services Selection Table

Routing by Dial Plan (Hybrid/PBX Only). Routing by dial plan is similar in concept to Direct Inward Dial (DID). It provides the ability to direct a call automatically to the proper destination for improved call distribution and call handling. Unlike a DID line, a PRI line (or T1 line) programmed for routing by dial plan can accommodate outgoing calls as well as incoming calls. As with DID operation, this feature is available only in Hybrid/PBX mode.

PRI Routing by Dial Plan. Routing by dial plan also allows multiple calls to a directory number. Concurrent incoming calls with the same Called Party Number can be delivered to a destination simultaneously.

The Dialed Number Identification Service (DNIS) is a service attribute of the Megacom 800 service. Based upon customer-selected parameters, such as area code, state, or time of call, it provides distinct Called Party Numbers for incoming 800 and 900 calls.

For each B-channel group, the system can be programmed for either routing by line appearance or routing by dial plan. With routing by dial plan, the Dial Plan Routing Table must be programmed to contain a series of patterns--the number of digits in the CdPN, network services on which to match, and a number of digits to add or delete for each match--in order to route the call to the proper destination.

If a B-channel group is programmed for routing by dial plan, all incoming calls to that B-channel group are routed in a DID-like manner and terminate on an SA button, on a single-line telephone, into a Calling Group queue, or at a Queued Call Console (QCC). When an incoming call arrives, its network service type and CdPN are compared to entries in the Dial Plan Routing Table. If no match is found, the call is routed to the programmed backup position for unassigned DID calls (normally the primary system operator). If a match is found, the CdPN is manipulated according to the Dial Plan Routing Table before matching it against the inside dial plan to identify a destination to which the call is delivered. If the manipulated CdPN does not match an inside extension, it is treated as an unassigned DID call.

If a fast busy tone is programmed as the routing destination for unassigned Direct Inward Dial calls, the call is rejected. This typically causes the network to return an intercept tone instead of a fast busy tone. If the number matches a destination that DID calls are not permitted to reach (for example, pool access codes, group page codes, line access codes, or the ARS access code), the call is routed to the programmed destination for unassigned DID calls (unless the backup is a fast busy tone).

The table below is a sample Dial Plan Routing Table. Note that in the sample table all incoming calls through the Megacom 800 service are delivered to an extension whose dial plan number is 1234. Entry 15 would be skipped because No Service is specified.

Sample PRI Dial Plan Routing Table

Entry

0

1

2

3...

15

Service

SDN

SDN

MEG800

 

No Service

# of digits in CdPN


7


10


10


 

[not specified]

Example #

555-1234

908-555-1234

 

 

 

Pattern

555

[none]

[none]

 

[none]

Digit deletion

3

6

10

 

14

Digit addition

[none]

[none]

1234

 

0

When routing by dial plan is used for an incoming call, if the programmed service, number of digits in the Called Party Number (CdPN) and patterns match those associated with the incoming call, the appropriate digit deletion and addition are performed. The process is as follows:

  1. The programmed service is compared with the B-channel service, if supplied. A match is found if the two services are equivalent or if the programmed service in the Dial Plan Routing Table is All Services. If a match is found, the system continues to search the entry. If no match is found or if No Service is specified, the system skips the entry and proceeds to the next one. If no service is supplied, the call is matched to No Service table entries.

  2. The programmed number of digits is compared with the number of digits in the actual CdPN. A match is found if the two numbers are equivalent or if the programmed number of digits is 0. If a match is found, the system continues to search the entry. If no match is found, the system skips the entry and proceeds to the next one. If the programmed number of digits is 0, any number of digits in the CdPN is acceptable.

  3. The programmed pattern is compared with the digits associated with the incoming call. If the pattern matches, the entry is tagged as a possible best match for the incoming call. It is possible that more than one entry can match the incoming call; the entry chosen is the one that matches on the greatest number of digits in the pattern. For example, if 555-2000 is the CdPN and the two patterns that match are 555 and 5552, the entry associated with 5552 is chosen as the best match. If the pattern is not programmed, it is considered a match with the number of digits in the pattern equal to 0.

  4. After the table is scanned and the best match is found, the programmed digit manipulation (addition and/or deletion) associated with the entry is performed. If the digit manipulation results in an invalid dial plan extension, the call is routed to the destination for unassigned DID calls.

  5.  

    When a call arrives on a dial plan routed PRI facility and its digits match an extension on the non-local dial plan, the call is routed to the appropriate non-local extension.

Characteristics and valid entries for the Dial Plan Routing table are as follows:

Display Operation. The telephone display provides call-related information about incoming PRI calls delivered over the B-channel, if available. Otherwise, it displays the line label and the digits dialed.

Hyphens are inserted between the digits on incoming calls (for example, 555-1234 for a 7-digit display and 123-555-1234 for a 10-digit display). Any other number of digits appears without hyphens.

A brief description of the display support for incoming calls provided follows (see Display for additional details).

 

PRI display support applies to 4400-Series, MLX, ETR, and MLS display telephones.

Display preferences for incoming private-network calls are set up by using the Extensions menu. This setup affects calls arriving on tandem PRI trunks. You can set up 4400-Series, MLX, and ETR display telephones to display the extension number of the caller on the remote system, the programmed label, or both the label and the extension number. If ANI/ICLID information is provided for an outside call, it appears instead of the extension number and/or label.See Display for additional details.

Topics
  Description
 
  Called Party Nunber (CdPN)
Calling Party Number (CPN)
Lines / Trunks
PRI
T1
DS1 Facility Options
Type of Service
Framing Format
Line Coding
Channel Service Unit
  Line Compensation
Signaling Mode
Tandem PRI Trunks
Tandem PRI Trunk Programming
PRI Programnming Options
PRI Programnming Options - PRI Telephone Number
PRI Programnming Options - Network Services Supported
PRI Programnming Options - Copy Telephone Number to Send
PRI Programnming Options - Telephone Number to Send
PRI Programnming Options - Test Telephone Number
  PRI Programnming Options - Timers and Counters
PRI Programnming Options - Terminal Equipment Identifier (TEI)
PRI Call Processing
Incoming Calls
Outgoing Calls
Network Selection Table
Call-by-Call Services Table
Station Identification - Automatic Number Identification
T1 Programming Options
T1 Programming Options - T1 Tie Trunk Connections
T1 Programming Options - T1 Routing by Dial Plan
System-wide Programming Options - Clock Synchronization
System-wide Programming Options - Clock Switching
  At a Glance
  Considerations & Constraints
 
  Incoming Calls
Outgoing Calls
  Mode Differences
Feature Interactions