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Features and Capabilities of Enterprise Voice


Topic Last Modified: 2012-10-18

Each Microsoft Lync Server 2010 Enterprise Voice feature and capability has its own set of planning considerations, deployment requirements, and configuration steps. The topics in this section are grouped by feature or capability such that you can plan to deploy each separately, either in a phased deployment or at some sites and not others, without concerning yourself with information and requirements that pertain to features or capabilities that you are not planning to deploy.

The following features persist from versions released prior to Lync Server 2010:

  • PSTN Connectivity

  • Exchange Unified Messaging (UM) voice mail


    The ability to use a hosted Exchange service provider to provide voice messaging to users is new to Lync Server 2010

The following Enterprise Voice functionality is new to, or has been enhanced for, Lync Server 2010:

  • Call admission control

  • Emergency services (E9-1-1)

  • Media bypass

  • Multiple gateway support

  • Caller ID manipulation

  • Outbound route translation

  • Private telephone lines

  • Common area phones

  • Analog devices

  • Voice resiliency

  • Call management and call handling

PSTN Connectivity

A Lync Server Enterprise Voice deployment supports calls to and from the public switched telephone network (PSTN). PSTN calls require that you configure a SIP trunk that connects Lync Server to an Internet telephony service provider (ITSP), to an IP-PBX on your local network, or to a PSTN gateway through the Mediation Server or a supported hardware Survivable Branch Appliance.

For details about the PSTN connectivity options supported by Lync Server, see PSTN Connectivity. For details about the outbound call routes that need to be configured between Lync Server and ITSPs, IP-PBXes, or PSTN gateways, see Planning Outbound Call Routing.

Exchange Unified Messaging Voice Mail

If you have deployed or plan to deploy Microsoft Exchange Server in your organization, you can use Exchange UM features to provide voice mail to Enterprise Voice users. For details about integrating Exchange UM, see On-Premises Exchange Unified Messaging Integration and Hosted Exchange Unified Messaging Integration.

Call Admission Control

Lync Server 2010 introduces call admission control (CAC) as a way to determine whether new calls can be established depending on available network bandwidth. For details about assessing your network sites, your network bandwidth, and configuring call admission control policies to manage bandwidth, see Call Admission Control.

Emergency Services

Lync Server supports enhanced 9-1-1 (E9-1-1), a feature that provides location information to dispatchers of emergency services. For details about E9-1-1 and associating Enterprise Voice users’ phone numbers with their physical locations, see Emergency Services (E9-1-1).

Media Bypass

Media bypass is a new feature of Lync Server that enables media from a Lync Server client to bypass the Mediation Server in order to be processed directly by an IP-PBX, SIP trunking provider’s Session Border Controller (SBC), or PSTN gateway. Media bypass is available only for certain types of calls. For details about configuring support for media bypass in your Enterprise Voice deployment, see Media Bypass.


Media bypass will not interoperate with every PSTN gateway, IP-PBX, and SBC. Microsoft has tested a set of PSTN gateways with certified partners and has done some testing with Cisco IP-PBXs. Certification for SBCs is underway. Media bypass is supported only with products and versions listed on Unified Communications Open Interoperability Program – Lync Server at

Multiple Gateway Support

In Lync Server 2010, a single Mediation Server can now control multiple PSTN gateways. In previous releases, there was a 1:1 relationship between a Mediation Server and a PSTN gateway. In Lync Server, when you define a call route, you specify the gateways associated with that route, but you do not specify which Mediation Servers are associated with the route. Instead, you use Topology Builder to associate each PSTN gateway with a Mediation Server or a pool of Mediation Servers. For details, see Multiple Gateway Support.

Caller ID Manipulation

Lync Server 2010 provides you with the ability to manipulate the caller ID information displayed on outbound calls. As you plan outbound call routes, consider whether to manipulate the caller ID for calls placed by certain users, groups, sites, or all users.

Outbound Route Translation

As in previous versions, Lync Server 2010 requires that all dial strings be normalized to E.164 format for the purpose of performing reverse number lookup (RNL) during call routing. Downstream components, such as gateways, PBXs, and SIP trunks, may require numbers in local dialing formats. As a result, in Microsoft Office Communications Server 2007, it was sometimes necessary to individually configure downstream components, or even reroute calls, in order to accept E.164 dial strings.

With Lync Server 2010, however, you can create one or more rules that assist in manipulating the Request URI E.164 format before the call is routed to the gateway. For example, you could write a rule to remove +44 from the head of a dial string and replace it with 0144 before the call is routed to a gateway.

Private Telephone Lines

Enterprise Voice users can now have a second, unlisted telephone number for receiving incoming calls. For details about private telephone lines, see Private Telephone Lines.

Common Area Phones

Lync Server introduces support for common area phones, which makes it possible to use Lync Server to provide phone service and unified communications functionality from common areas, such as building lobbies. For details about planning for common area phones in your Lync Server environment, see “Choosing New Devices” in the “Planning for Devices” section of the Planning documentation..

Analog Devices

Lync Server now supports analog devices in the Enterprise Voice environment. Analog devices include analog phones or analog fax machines connected to an analog port of a gateway or a PBX; ATA gateways with 2 to 4 analog ports into which analog devices can connect and which are connected to a PSTN gateway. For details about integrating analog devices into your Enterprise Voice deployment, see Planning to Deploy Analog Devices in the Planning documentation.

Voice Resiliency

Branch site voice resiliency is the ability of a branch site to provide continuous Enterprise Voice service so that users can continue making and receiving calls, even if the central site or the WAN link to its central site becomes unavailable. For details about planning for a resilient Enterprise Voice deployment, see Planning for Enterprise Voice Resiliency, Planning for Central Site Voice Resiliency, and Planning for Branch-Site Voice Resiliency.

Call Management and Call Handling

Lync Server includes call management features that affect how incoming calls are routed and answered. For example, you can enable call parking and specify what happens to incoming calls to unassigned phone numbers.

You can continue to use the feature from Microsoft Office Communications Server 2007 R2 in which you configure users to act as delegates for their manager’s incoming calls. You can also continue to configure routing and queuing of incoming calls to groups of designated users, called response groups. New functionality for response groups includes the ability for agents to handle incoming and outgoing calls anonymously and for agents using Microsoft Lync 2010 Attendant to answer waiting calls in any order. Lync Server 2010 also offers integrated manageability, more flexible IVR configurations and prompts, and a web service that supports customized agent consoles.

For details about planning for these call management features, see Planning for Call Management Features.