# About Voice Clusters

A cluster is a group of interconnected elements that are configured together in such way that it appears to the end users that they are connected to a single large system. A user can make a call from one system in the cluster to another simply by dialing an extension number. For calls within the cluster, the phone displays present the calls to the users as if the calls were internal to a single system. And, features, such as Message Waiting Indication and Group Paging, are supported across the cluster.

Each element in the cluster shares the directory entries of all the other elements and system programming is standardized across all the elements. When network elements are configured in a cluster, you can

- move a telephone directory number to any extension in the cluster (i.e., you can move a user's telephone to an extension on any other element in the cluster and allow the user to retain the same directory number),

- move a directory number to any extension in the cluster without changing ARS programming, and

- call any local directory device (extension) in the cluster without dialing ARS leading digits.

MiVoice Business cluster elements are interconnected via IP trunks and/or DPNSS over T1 trunks. Unlike network elements, cluster elements share the same Primary Node Identifier (PNI). Calls are routed between the cluster elements using Cluster Element Identifiers (CEIDs).

## Local and Remote Directory Numbers

The directory numbers in the telephone directory forms of each element are classified as either local directory numbers or remote directory numbers. A local directory number belongs to a device, such as an IP phone, that is physically connected to that element. A remote directory number belongs to a device that is connected to another element in the cluster. Therefore, the directory number for a local device on element A, is a remote device in relation to element B and its directory number appears in the Remote Directory Numbers form of element B. Conversely, a local device on element B would appear in the Remote Directory Numbers form of element A.

## Cluster Element Identifier (CEID)

Each element in a cluster is assigned a different cluster element identifier (CEID) digit string. The CEID digits are used to route calls between the cluster elements. An element that is a member of a cluster is called a cluster element.

You must assign each cluster element a unique 1- to 7-digit CEID digit string in its Cluster Elements form. The Cluster Elements form of each cluster element must also list the CEID digit strings of the other cluster elements. You also associate each CEID digit string with a CEID index in this form. Assigning the CEID index of a remote cluster element to a directory number, classifies that directory number as a remote directory number.

When a user on cluster element A dials the remote directory number of an extension on cluster element B, cluster element A automatically inserts the CEID digits of cluster element B in front of the dialed directory number. ARS then routes the call to the remote cluster element based on the CEID digits. The user does not dial the CEID digits to call a remote directory number. The CEID digits do not appear in set displays for calls within the cluster.

## Characteristics of a Cluster

A cluster has the following characteristics:

- MiVoice Business elements are networked together via IP trunking or DPNSS protocol.

- A cluster can be part of larger MSDN/DPNSS network

- You manage a cluster and its telephone directory through System Data Synchronization using Remote Directory Number Synchronization.

- A cluster has a uniform number plan.

- All cluster elements in the cluster have the same PNI.

- Each cluster element in the PDN network has a unique Cluster Element Identifier (CEID) digit string. The CEID digit string is a 1 to 7-digit identifier that allows calls to be routed between the cluster elements.

- ARS routing digits (CEID digits + extension number) on each cluster element must be the same length

- Each cluster element is assigned a Feature DN that supports common features, such Message Waiting Indication and Group Paging, across the cluster.

- The maximum size of a single cluster (with all elements running 3300 Release 8.0 UR3 software or later) is 999 elements. An element in the cluster can be connected to 249 other elements via IP trunking. For cluster sizes over 250 elements, a multi-hub configuration in which calls between peripheral elements in the cluster transit through designated hubs is recommended.

- A 999-node cluster (as specified in the License and Option Selection form) of MiVoice Business systems will not support SX-2000 systems in the cluster.

- On cluster elements running 3300 ICP Release 6.0 software or later, you can use the System Data Synchronization (SDS) feature to configure the member elements with consistent data across the cluster. For example, you can use SDS to configure the Feature Access Codes to be the same on all the cluster elements.

## What Devices can be Assigned Remote Directory Numbers?

You can assign the following devices and software entities with remote directory numbers:

- hunt groups (including ACD, voice mail and phantom groups)

- Broadcast Group
  A directory number programmed to appear on multiple devices constitutes a broadcast group. There are two types of broadcast groups: Non-Prime Line and Prime Line. A Non-Prime Line group is a directory number programmed on one or more devices that is not the prime line on any device. A Prime Line group is a directory number programmed on button 0 of a phone. Server-based variants of MiVoice Business that use x86 processors, MiVoice Business for Industry Standard Servers MCD-ISS), Multi-instance MiVoice Business, and Virtual MiVoice Business, up to 250 appearances of the directory number can appear on one or more devices. For all other 3300 ICP/MiVoice Business call control platforms, up to 32 appearances of the directory number may appear on one or more devices.s (prime and non-prime)

- single-line sets

- 5000, 5200 and 5300 series IP Phones

- 5140 and 5240 IP Appliances

- 5224 IP Phone

- 5660 IPTs

- 6900 series IP Phones

- Navigator Phone

- Teleworker Solution

- IP Conference Units

- IP Consoles

- IP Turret

- System speed calls

- ACD II agent id's

- ACD paths

- destination directory number of a hotline

NOTES

- Configure only those devices that you intend to move from one cluster element to another as remote directory numbers.

- All DPNSS features function with remote directory numbers in the same manner as they do with standard directory numbers.

Related Topics

- About Networks

- How Calls are Routed in a Cluster

- Managing the Telephone Directory