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Let's Talk: Considerations When Getting Ready to Deploy Lync Enterprise Voice

Posted by Kevin Gulley

Sep 10, 2014

Since being awarded top honors in the recent Gartner UC Magic Quadrant, Microsoft Lync has been all the buzz in the UC market.  While companies have been rapidly deploying Lync for presence management, collaboration, IM and conferencing (mostly intra-company capabilities), when it comes to true enterprise voice deployments - in which Lync replaces the traditional Private Branch Exchange (PBX) telephone system and extends beyond the organization - companies are moving more slowly.Deploying_Lync_Enterprise_Voice_Multiple_Devices

This makes sense, as prior to executing on a project like this businesses need to think through issues of interoperability, security, policy and management - not to mention the software, servers, connections to the public phone network, endpoint device requirements, rollout schedule and training.  However, there is no time like the present to start thinking through these issues, especially with employees that have already been given a taste of UC pushing their organizations to extend Lync outside the company.  There are multiple options for deploying Lync Enterprise Voice - hosted, internally managed or hybrid - but for the sake of this post I’ll touch on some of the building blocks of a Lync Enterprise Voice deployment as if you were deploying it internally.

Planning for a Successful MS Lync Enterprise Voice Roll-out

Lync Enterprise Voice provides businesses with all the functionality that has traditionally been handled by a PBX, including things like inbound and outbound calls, desk-to-desk calls, conference calling, voice mail, attendant functionalities, etc..  By adding Lync Enterprise Voice (OK, I’m already sick of typing that, from now on it is LEV) to the basic Lync deployment, which offers the ability to conduct meetings via voice or video, IM, collaboration and presence management software, businesses will be able to deliver a truly unified communications architecture.

As with all mission-critical deployments, it is important to spend the time to properly plan in terms of policies and configurations that will govern the platform.  Microsoft offers a planning tool, cleverly called the Microsoft Lync Planning Tool, that walks users through their actual implementation and can provide details on all aspects of the deployment from planning, to hardware, to network considerations.  In terms of planning, at the minimum businesses need to consider:

  • Your site deployment approach - Central location vs Branch locations

  • The number of employees at each and the number of calls they make per day

  • Estimated bandwidth and WAN throughput requirements based on increased load

  • Increased server capacity as necessary to support your users

  • Company approach to security, survivability, redundancy and availability

Software - Yup, You’ll Need A Different CAL for Enterprise Voice

My experience with Microsoft is that you need a doctorate to understand their licensing model, but it’s not too bad when it comes to upgrading Lync to manage voice.  As far as servers are concerned, MS says:

A license must be assigned for each instance of the server software that is running the front-end server role—all other roles do not require a license. Lync Server 2013 is licensed in one edition for all deployment scenarios.

Regarding the Client Access Licenses (CALs), users utilizing LEV (see, I told you) will need a Lync Plus CAL, which is an additive upgrade to the Standard CAL.

You can get all the scoop on licensing you need by downloading the Lync Pricing and Licensing Guide.




Download Lync Enterprise Voice for Dummies (free courtesy of Sonus Networks) to gain insight into Lync deployment scenarios, applications enabled by Lync, case studies, SIP, SBC’s and more




Additional hardware and server requirements are necessary to enable LEV, and these will vary depending upon your deployment scenario and how much more computing power you will need to support your employee base.  At the very least, you will need a Lync Mediation Server.  According to Microsoft:

Mediation Server is a necessary component for implementing Enterprise Voice and dial-in conferencing. Mediation Server translates signaling, and, in some configurations, media between your internal Lync Server infrastructure and a public switched telephone network (PSTN) gateway, IP-PBX, or a Session Initiation Protocol (SIP) trunk. You can run Mediation Server collocated on the same server as Front End Server, or separated into a stand-alone Mediation Server pool.

When using LEV companies typically connect their branch locations to the PSTN via the Central Site over a Wide Area Network (WAN).  In other words, calls go from the branch to the central data center and then to the phone network and vice versa.  An additional option to consider for these companies is installing a Survivable Branch Appliance (or Survivable Branch Server depending on the size of the branch office).  These devices enable direct connectivity to the PSTN in case the WAN link between the branch and the central office suffers an outage.

SIP Trunking is the Way to Go for PSTN Connectivity

One of the biggest decisions businesses need to make is how to offload voice calls from their network to the PSTN (Public Switched Telephone Network).  While there are options for connectivity,  including using standard TDM (time division multiplexing) telephone services, and the decision for any business depends on a number of variables including existing infrastructure, project timetable and budget, all things being equal, utilizing SIP Trunking is the clear choice for deploying Enterprise Voice.  Not only do the large majority of businesses report savings of more than 25% as a result of deploying SIP Trunking, it provides a number of additional benefits, including:

  • Consolidation of PSTN connectivity into a single central site

  • Less equipment to buy, manage and deploy

  • Lower calling costs

  • Potentially eliminating calling costs in lieu of bandwidth costs with some providers

The Session Border Controller (SBC) - Keeping Things Secure and Running Smoothly

A key element of a successful and secure external LEV deployment is a Session Border Controller.  SBCs sit on the edge of the network, between the company’s and the phone company’s network, and provide a number of crucial security and mediation functions to keep a Lync Enterprise Voice deployment running smoothly.  


SIP networks are IP Networks and subject to the same security issues as any other IP network.  As we covered in this post:

Normally, you’d use a firewall to protect the network against unwanted intruders but they are ineffective on a SIP network. “A firewall can’t look and see the start and end of a session or a call,” Konrad says. “It doesn’t understand things like caller ID and the concept of sessions that exist for a short time and then disappear.”

SBCs, on the other hand, do understand the intricacies of SIP and are able to open up pathways for legitimate calls to go through, then close them down the instant the call ends. “SBCs guard the border,” he says, just as firewalls do for data networks. SBCs can also perform encryption, he notes, such as for sensitive voice or video calls that traverse the PSTN.

Communication Between Two Networks

SBC also take care of translating between various SIP dialects.  As we reviewed previously:

”The issue is the SIP equipment you have in your network, such as a router or PBX, may not implement the protocol in exactly the same way as the carrier that provides your SIP trunks,” Konrad says. The SBC provides a translation, essentially, that enables the two to effectively communicate with one another. That can apply equally to voice calls as well as video, such as in instances where you want to tie in someone outside the company to a video call and need to communicate with that person via the Internet.

Don’t Forget the Endpoint Devices

I was having a conversation with a communications consultant recently and he told me a story about a 500 seat Lync deployment he’d heard about.  It was going smoothly, testing well, every employee even received a new laptop.  However, they forgot to order headsets and when the deployment went live there were a whole bunch of people in their cubicles yelling into their computer screens.  

There are a number of options for endpoints, including Lync-certified IP phones, hardwired and wireless headsets, of course Smartphones and tablets, and yes, even your laptop speakers.  

To get more insights into deploying Lync Enterprise Voice, download the eBook Lync Enterprise Voice for Dummies.

Topics: Technology, Voice, Business Case, Security

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