[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-07-14

This section describes the background concepts you should know for planning to deploy Enterprise Voice call management features.

Call Park

Deploy Call Park if you want Enterprise Voice users to be able to do any of the following:

  • Put a call on hold and then retrieve the call from the same or another phone.

  • Put a call on hold to transfer it to a department or general area, for example, to a sales department or a warehouse where there is a common area phone.

  • Put a call on hold and keep the original answering phone free for other calls.

When a user parks a call, Communications Server 2010 transfers the call to a temporary number, called an orbit, where the call is held until it is retrieved or it times out. Communications Server sends the orbit to the user who parked the call. To retrieve the parked call, the user can dial the orbit number or click the orbit link or button in the conversation window or in conversation history.

The user who parked a call can notify someone to retrieve the call by using an external mechanism, such as instant messaging (IM) or a paging system, to communicate the orbit number to someone else. The user who parked the call can leave the conversation window open to receive notification when the call is retrieved.

Because orbit ranges are globally unique, it is possible to retrieve calls from any Communications Server site or PBX phone if routing is configured appropriately. If no one retrieves the call within a configurable amount of time, the call rings back to the person who parked it. If that person does not answer the ring-back, the call is transferred to a fallback destination, such as to an operator. If no one answers the transferred call, the call is disconnected. The orbit is freed when the call is retrieved or disconnected.

When you deploy Call Park, you need to reserve ranges of extension numbers (orbits) for parking calls. These extensions need to be virtual extensions: extensions that have no user or phone assigned to them. You then configure the call park orbit table with the orbit ranges and specify which Application service hosts the Call Park application that handles each range. Each Communications Server 2010 pool where the Call Park application is deployed and configured can have one or more orbit ranges. Orbit ranges must be globally unique across the Communications Server 2010 deployment.

An administrator also configures other Call Park settings, such as where calls are redirected if they time out and whether the caller hears music while parked. The administrator can also specify the music file to play while the call is on hold.

The Call Park application is a component of Enterprise Voice. When you deploy Enterprise Voice, the Call Park application is installed and activated automatically. Before you can use Call Park, however, the Enterprise Voice administrator must configure it and enable it for users through voice policy.

Response Group

If your organization has groups of people who answer and manage certain types of calls, such as for customer service, an internal help desk, or general telephone support for a department, you can deploy Response Group to manage these types of calls. The Response Group application routes and queues incoming calls to designated persons, who are known as agents. You can increase the use of telephone support services and reduce the overhead of running these services by using Response Group.

When a caller calls a response group, the call is routed to an agent based on a hunt group or the caller's answers to Interactive Voice Response (IVR) questions. The Response Group application uses standard response group routing methods to route the call to the next available agent. Call routing methods include serial, longest-idle, parallel, round robin, and the new Attendant routing, in which all agents are called at the same time for every incoming call, regardless of their current presence. If no agents are available, the call is held in a queue until an agent is available. While in the queue, the caller hears music until an available agent accepts the call. If the queue is full, or if the call times out while in the queue, the caller might hear a message and then is either disconnected or transferred to a different destination. When an agent accepts the call, the caller might or might not be able to see the agent's identity, depending on how the administrator configures the response group. Agents can either be formal, which means that they must sign in to the group before they can accept calls routed to the group, or informal, which means that they do not sign into and out of the group to accept calls.

The Response Group application uses an internal service, called Match Making, to queue calls and find available agents. Each computer that runs the Response Group application runs the Match Making service, but only one Match Making service per Communications Server pool is active at a time--the others are passive. If the active Match Making service becomes unavailable during an unplanned outage, one of the passive Match Making services becomes active. The Response Group application does its best to make sure that call routing and queuing continues uninterrupted. However, when a Match Making service transition occurs, any calls that are in transfer at the time are lost. For example, if the transition is due to the Front End Server going down, any calls currently being handled by the active Match Making service on that Front End Server are also lost.

Response Group scales well to departmental or workgroup environments (for more details, see Capacity Planning for Response Group) and can be deployed in entirely new telephony installations. It supports incoming calls from the Enterprise Voice deployment as well as from the local carrier network. Agents can use Microsoft Communicator, Communicator Phone Edition or Attendant to take the calls routed to them.

The Response Group application is a component of Enterprise Voice. When you deploy Enterprise Voice, the Response Group application is installed and activated automatically.


Deploy the Announcement application if you want to configure how incoming phone calls are handled when the dialed number is valid for your organization but is not assigned to a user or phone. You can configure the Announcement application to transfer these calls to a predetermined destination (phone number, SIP URI, or voicemail) or play an audio announcement or both. Using the Announcement application avoids the situation in which a caller misdials and hears a busy tone or the SIP client receives an error message.

When you deploy the Announcement application, you need to configure the unassigned number table. The unassigned number table contains ranges of phone numbers that are valid for the organization and specifies which Announcement application handles each range. When a caller dials a telephone number that is valid for your organization but is not assigned to anyone, Communications Server 2010 looks up the number in the unassigned number routing table, identifies which range the number falls in, and routes the call to the Announcement application specified for that range. The Announcement application answers the call and plays an audio message (if you configured it to do so) and then either disconnects the call or transfers it to a predetermined destination, such as to an operator. You can use Communications Server Management Shell cmdlets to configure multiple audio messages or transfer target destinations.

How you configure the unassigned number table depends on how you want to use it. If you have specific numbers that are no longer in use and you want to play messages that are tailored for each number, you can enter those specific numbers in the unassigned number table. For example, if you changed the number for your customer service desk, you can enter the old customer service number and associate it with an announcement that gives the new number. If you want to play a general message to anyone who calls a number that is not assigned, such as for employees who have left your organization, you can enter ranges for all the valid extensions in your organization. The unassigned number table is invoked whenever the caller dials a number that is not currently assigned.

In Communications Server 2010, the Announcement application is automatically installed with the Response Group application. The Announcement and Response Group applications are standard components of an Enterprise Voice deployment: When you deploy Enterprise Voice, both of these applications are automatically deployed.