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

Topic Last Modified: 2010-07-18

Voice over IP (VoIP) is a software-based alternative to traditional PBX-based telephony. Though the VoIP call experience is similar to the traditional telephony experience, the Microsoft Communications Server 2010 VoIP solution, Enterprise Voice, includes features that enable richer communication and collaboration. For example, your Enterprise Voice deployment can be configured to enable Microsoft Communicator "14" clients, including Microsoft Communicator “14” Phone Edition to allow users to view enhanced presence information or location information for contacts in your organization’s address book. Some Communications Server 2010 features are enabled through integration with other Communications Server 2010 workloads and with Microsoft Exchange Unified Messaging (UM).

New to Communications Server are the following Enterprise Voice enhancements for users, more effective call handling (routing and answering), and additional return on investments (ROI) for your organization:

Users can place emergency calls that provide detailed physical location information to the Public Safety Answering Point (PSAP) that dispatches emergency services to the callers in distress.
The ability for users to park a call on one phone, and then retrieve the call from another phone.
Routing and handling of calls placed to telephone numbers that are valid but not assigned to any user or phone in your organization.
Support for users to have a second, private telephone line on which they can be reached directly.
The ability for a single Mediation Server to control multiple IP-PSTN gateways. For example, gateways deployed at branch sites can now depend on a Mediation Server deployed at the central site.
New gateway topology options and the introduction of hardware solutions—a survivable branch appliance—to address central site and branch site Voice resiliency.
The ability to create one or more rules that assist in manipulating the Request URI prior to routing it to the gateway to reduce the configuration required on the gateway to manipulate phone numbers.
Flexible manipulation of the caller ID for outbound calls.
Better scalability and high availability because calls can now be load balanced across a pool of Mediation Servers.
Reduced administrative overhead for hardware load balancers with the introduction of DNS load balancing to handle SIP traffic and media traffic for Front End pools and Director pools.
Support for media bypass, in which media is processed by a media termination point other than the Mediation Server. Media bypass can help reduce latency during calls, needless translation, the possibility of packet loss, and the number of points of potential failure. Media bypass can also reduce the number of Mediation Servers you need to deploy, lower bandwidth usage, and improve scalability.

With Communications Server, your Enterprise Voice users can also continue to do the following, as they did in previous releases:

Place calls to and receive calls from their computers or with USB telephones or other compatible devices.
Place calls to and receive calls from telephones connected to a PBX or on the PSTN.
Place calls by clicking a contact name in Outlook or Communicator rather than needing to remember or look up telephone numbers.
Switch between communication modes-instant messaging, conferencing, voice, e-mail, and other communication modes-as needed.
Have incoming calls ring simultaneously on all of their communications devices, enabling users to answer wherever they have an Internet connection and on whichever device is most convenient.
Place calls that traverse your organization’s firewall when users are outside or inside the firewall.
Forward calls or delegate calls to other users or response groups, and use other call-control features.
Retain existing telephone numbers.
Handle high-volume calls, with advanced features such as consultative transfers by phone or IM, transfers with notes, and availability checking.

In addition to the aforementioned productivity enhancements for users, Enterprise Voice continues to provide the following benefits for your organization:

The ability to integrate with existing routers, gateways, PBXs, remote call control (RCC) solutions, and telephones that are compatible with Communications Server or to replace traditional telephony devices with software.
Support for USB-attached phones and other telephony devices that support integration of the user’s phone with other collaboration and enhanced presence features of Communications Server 2010.
Use of smart, least-cost routing algorithms for calls to the public switched telephone network (PSTN).
Centralized administration using software tools.
Distributed architecture that reduces bottlenecks and the likelihood of single points of failure.
Integration with Exchange Unified Messaging (UM) to provide voice mail, voice messaging, e-mail messaging, call answering, subscriber access, call notification, and auto attendant services.
Connecting your on-premises voice network to one or more service providers who offer PSTN origination, termination, and emergency services, instead of deploying IP-PSTN gateways within your organization’s network.

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