Can Lync replace my company’s PBX?

Here’s the one million euro question! from my personal opinion the answer is:

“Yes it can, but…”

This is a very important post for me. It expresses in this lines, 4 years of personal experience investment and I hope I can help corporate decision makers evaluating and considering Lync.

I grouped 5 points to evidence Lync response has a corporate IP-PBX, but remember that has much more capabilities like video and content sharing.

Note: Don’t think that this is a market revolution from Microsoft. All major IP-PBX vendors have similar solutions. To be completely sure in choosing MS, compare and even test with one other vendor at least. If you read my blog, you already find some reviews.
End user devices

Remembering my rule: “UC is all about user experience”. Lync is revolutionary compared to traditional communications, but it does not have to be disruptive when introducing in a company.

The richest devices are the software clients for Windows and Mac with all capabilities (IM, voice and video conferencing and content sharing) anywhere and you can also find interesting solutions for mobile devices.

This doesn’t mean the end of the deskphone. You still want to have these devices on meeting rooms, manufacturing areas, etc. and provide communications to personal with no or less computer experience. Another reason is you don’t need a personal computer, and these phones are a lower investment.
There are several deskphones from 3rd party vendors (Polycom, Aastra, Snom, Plantronics, …), from a simple keyboard/handset style to a model with a lync client display including the contact pictures. On the lowest model you got presence and voice calls capabilities.

Other interesting solutions from 3rd party are some gateways that allows you to connect other phones that are not Lync enabled (Audiocodes, Net,…). Two advantages from those: you can user some of your existing IP phones and even the analog ones, and you can connect softphone from other brands and platforms, like Linux desktops.

There is one particular device that you should carefully consider: the company’s receptionist (or even a secretary). Although Lync is more than a PBX, organizations will still have use of switchboard operators working at an attendant console, to handle, put on hold/queue, retrieve and forward multiple calls. Microsoft has a software client called Lync Attendant for this, but you might want to use a more traditional hardware based solution like a snom370 with expansion panel (you can get up to 138 buttons with speed dial). The big advantage is that receptionists often don’t need additional training on a physical phone. Like Snom there are other 3rd party solutions that report similar capabilities, but I never tested them: Multimedia Attendant, Trio Enterprise 3.1,  Vision 80/20, or ZyCall Switch

Public network connectivity

This is the key decision for a Lync deployment has a full solution. You need to be sure that you can make and receive calls outside your company, especially the PSTN. Microsoft and partners will say no problem, but you must have to be sure. As the decision it’s you neck that is at risk.

VoIP communications outside the Lync infrastructure are done by the mediation server. From this point forward you have two main options to connect to your Telecom Provider:

  • Using 3rd party IP gateways – more simple or complete in features, they connect Lync using any available connectivity (SIP Trunk, PRI/BRI, ISDN). There is a large list of official choices available to connect directly or through your IP-PBX.
  • The simple and less expensive is a direct connectivity using a SIP trunk. The list of providers is growing, but your local and reliable Telecom provider might not give you that choice (I’m not going to discuss that now…it’s somehow a technical and political issue), so you might want to go to the first option or use an SBC.

Lync also implemented emergency call support, but I’m not sure if it’s supported in European countries. To comply with legal rules you must be able to provide the location of the phone call, and this is a challenge not only for the mobile Lync users, but it becoming also a problem for the existing telephony leaders and the Government itself

I’m not going to detail other types of Lync external connectivity, like federation for IM and voice and even video interoperability… and there is lot of 3rd party solutions available, some already mentioned on my blog.

Office locations

Multiple office locations are not a problem for Lync. You can simply use wan links and let devices connect using IP/DNS or deploy more than one Lync pool and multiple servers and connect them. Whether you have multiple/separate domains, telephony can be shared easily.

One thing that was missing (and criticized by the competition) was bandwidth control for wan traffic. QoE can guarantee minimum traffic for calls and CAC implements policies that prevent Lync user calls to flood your IP links and minimize impact on other application services.

Office survivability (in case wan link failures) is discussed on the next topic.

Scalability, reliability and resilience

How critical are voice communications for your company? … No need to answer that :).

Is Lync capable of managing your large, worldwide spread company? I guess so. Let’s check the facts:

  • Lync can scale to a very large number servers and pools and ensure high availability and load balancing.
  • You can use Lync SBA at branch offices, provided by 3rd party manufacturers. These products can provide Voice PSTN connectivity in case of wan outages.
  • There’s a study that shows a 100% uptime of Lync with 4’107’951 calls in 13 days. I know… it’s just a lab but the fact is that the number of Lync customers is increasing in number and size.

This post is becoming too large (and exciting to write…), so I will just say on this point that you can find any type of 3rd party solutions that can respond to your needs: auto attendants, contact centers, communication accounting and billing, video recording streaming, translation, voice recognition, GPS, SMS,…


In conclusion, with Lync we can have almost all well-known (traditional) corporate phone capabilities, but you add presence, messaging, video, content sharing and mobility. All capable of integrating with your desktop environment and business applications (CEBP), enabling a true corporate collaboration. This is the first part of the post question: Yes it can replace or enhance your existing voice infrastructure. It’s really worthy.

Now let’s talk about the ‘but…’

You noticed one particular set of words in a different color. The ‘3rd party’ factor is important. Unlike the competition (Cisco, Avaya or Alcatel), Microsoft mainly provides the software solution, and you have to contact different manufacturers according to your needs. This might represent additional knowledge requirements and support contracts.

Another challenge is the management: it’s not just a Windows server. I has voice, video and real-time communications with a lot of connected users that don’t want their phone unavailable at any time.

If you think that you will replace your Telecom provider and save money by delivering responsibilities to your IT (sysadmins and helpdesk), think six or more times. Even after a 6 months trial, they are not ready for a production environment. There’s a lot of troubleshooting: it’s not just TCP packets, High CPU or databases performances. There are protocols (SIP, STUN, ICE,…), network bandwidth, voice and video codecs (RTaudio, G.711, H.264, …) to analyze from the desktop, throw the servers and to the other side of an external network or PSTN.

If you think about how much painful can be an Exchange user, let’s now add poor voice call quality, conference calls disconnecting, video freezing or failing to your team daily tasks: ‘do you feel lucky?

I came from 16 years from IT administration, and after 4 years with Microsoft OCS/Lync, Cisco, Polycom I’m still learning a lot about VoIP, technologies standards and protocols. And I still have a lot to learn about joining the IT and Telecom world (at least another 10 years…)

My recommendation is: if you want to go with Microsoft Lync, carefully choose one (or two) partner capable and with experience in Lync, telephony and the Telecom service providers.
Your traditional MS partner might not have the experience to manage and deal with your voice provider, and your Telecom provider might not have the IT experience to deploy and manage a Lync server infrastructure…. Though choice!

I end this post with the complete answer:

‘Yes it can, but… you better know well how and when to.’


2 thoughts on “Can Lync replace my company’s PBX?

  1. Lennart Bauer 10/12/2011 / 22:50

    A little advert 🙂
    For another Lync attendant, take a look at http;://

    • LuisR 11/12/2011 / 15:26

      yes I have you on my list, but sorry for not mentioned it… never had time to test/review in detail.
      But I post your comment, so everyone know about it

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