Dec 20

Global Microsoft Lync 2013 roll-out and conferencing

Already starting from OCS server, Microsoft supports conferencing (audio, video and web) in it’s UC solution. More and more organizations are conferencing on the Lync platform and use it to save costs on their conferencing. With multinationals more than often 100.000’s minutes per month are spend on conferencing. And very often these organizations only use a few local dial-in numbers on Lync.

If you choose the right global voice provider (e.g. BT), they can supply you with local dial-in numbers for conferencing. This can be delivered in 170+ countries. So what do you need in order to achieve such a solution:

  1. SIP trunking with local dial-in numbers
  2. SBC (session border controller).  A good description can be found on the NextHop blog, written by MVP Steven van Houttem. “What is an SBC and do I need it?”
  3. Lync 2013 Enterprise Pool (Standard Pool is also possible but not seen a lot with multinational organizations)


  1. proper sizing of AVMCU has to be done based on amount of meetings, participants and duration and meeting size (default max 250, on dedicated AVMCU’s up to 1000 simultaneous participants)
  2. proper sizing of SIP trunk to carry all voice traffic during peak hours.

An illustration of the solution can be found below:

Lync and global conferencing

Lync and global conferencing

On the bottom left the Lync datacenter can be found with:

  • Enterprise Pool containing
    • AVMCU on the Front-End servers (hosting the conferences),
    • Mediation Server for SIP interconnectivity
  • In the DMZ are:
    • Edge Server for connectivity with remote clients and mobile clients
    • SBC for connectivity and demarcation of the service provider central SIP trunk

Branch site containing:

  • A Surviveable Branch Applicane (SBA) (more info in: SBA deployment and testing). This can be used for survivability in case the WAN connection fails and/or to connect local PSTN and decentralized SIP trunks
  • Lync Client users and/or Lync Phones

Ok, now let’s see how everybody connects when a conference is organized:

  • On the top: any normal phone user (pstn or mobile), will have received a local dial-in number toll or toll-free (e.g +3120xxxxxxx for NL, +49xxxxxxx for DE, +32xxxxx for BE etc.). They don’t have to call an international number to dial into the conference even though the Lync datacenter might not be in their country
  • On the left: Lync 2013 desktop clients and Lync 2013 mobile clients join via the internet and external users can connect via federation or via Lync Web App.
  • On the bottom right: users in the branch office can (option 1) connect via the WAN to the datacenter or (option 2) via the SBA and the PSTN/decentral SIP trunk, depending on configuration and survivability mode (in case of WAN failure)

So in this picture the only users that need the old fashion dial-in conferencing are external users not in possession of Lync (or don’t want to use Lync Web App) and travelling users (i.e. in the car etc). Since most conferences are internal in an organization, easily 50 to 80% of PSTN minutes can be reduced. Additional cost elements are the Lync infrastructure, SIP trunk and network connectivity (SBA is not necessary). But after collecting all data, this is a very easy business case to make in multinational organizations.

So what do we need to configure in Lync to have local dial-in numbers when a user sends an invite when organizing a meeting.  High Level the steps are follows:

1. order a SIP trunking with a global provider with local numbers in the countries you like (i.e. matching your own presence, where you have office or customers / partners0

2. install a Lync Qualified SBC. Approved and tested Microsft Lync vendors can be found at the UCOIP page for Lync. Look for Infrastructure and Session Border Controllers. Well known are Audiocodes, Sonus and Acme Packet. Note: Cisco CUBE has not been tested, since Cisco does not want to submit their products to Microsoft testing.

3. Lync Server 2013 Control Panel.

  • Configure conferencing policy
  • Configure local dial-in numbers as per indicated in this blog of Elan Shudnow, this is still for Lync 2010, but in Lync 2013 the concept is the same. I’ll update this blog when time is available to make some Lync 2013 screenshots.

A detailed Microsoft section on Configuring Conferencing settings for Lync 2013 server can be found on Technet. 

After this is done. All the user has to do to organize a meeting is the following:

In Outlook:

Outlook, start Lync 2013 meeting

Outlook, start Lync 2013 meeting

Outlook, organizing a Lync 2013 meeting

Outlook, organizing a Lync 2013 meeting












This will look like the above and can be extended with the 170 local dial-in numbers (toll and toll-free). When a users wants to join the meeting with his Lync client or Lync Web App al he has to do is push the “Join Online Meeting” link (for audio/video and desktop sharing meeting). Audio only participants can use the local dial-in numbers.

In a future a blog i’ll go into multiple regional Pool (i.e. EMEA, Americas, APAC) conferencing setup and considerations. Note that a conference is hosted on the pool where the organizer is homed upon. For local dial-in numbers a separate numbering dial-in range per region would be used.

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