Can you provide more details around whether or not I need to deploy a Survivable Branch Appliance for my Lync deployment?

This question was asked by a college based out of Florida looking to deploy Lync for their 1500 faculty and staff.  They had redundant WAN links and wanted to determine what a SBA provides. Screenshots from Lync product team.

If I have redundant WAN links, what benefits does a SBA provide for my branch offices?

An SBA provides the following benefits:

  • Local SIP Registrar – don’t have to carry this over the WAN
  • Normal/Failover mode – WAN primary and PSTN as backup for failover
  • SIP Proxy & Routing engine
  • PSTN connectivity
  • Voicemail routing
  • PSTN re-routing – auto re-route to PSTN during WAN failure and auto failback when WAN is restored
  • Centrally provisioned
  • Call Detail Records
  • Replicated CMS
  • Branch office users hosted on SBA
  • Up to 1000 user support


What are my Branch Office options for Lync Server?

You have three recommended options available to you.The first is no SBA for 25 users or less.  The second is an SBA for 26-1000 users and the third option for 1001-5000 users is a Survivable Branch Server or Lync Std Edition Server with a Media Gateway. For remote sites with more than 5000 users it is recommended to deploy a full Lync infrastructure with a separate pool.

The idea here is you could use WAN as your primary and have a fallback for PSTN for high availability. For the small branch scenario, some UC phones allow for dual registration where you could fall back to an alternate VOIP provider is need be.




Does an SBA provide inbound and outbound dialing during a WAN failure?

End user experience when using failover to PSTN.


The answer is yes. Here are the features that work during resiliency mode in the branch office:

  • PSTN Inbound and Outbound calls
  • Intra-Site calls, Inter site calls (PSTN Rerouting)
  • Hold, Retrieve, Transfer
  • Authentication, Authorization
  • Voicemail Deposit (Redirect to ExUM in Data Center)
  • Voicemail Retrieve (through PSTN)
  • Call Forwarding, SimulRing, Boss-Admin, Team-call
  • Call Detail Records (CDR)
  • All 2 Party Intra Site communications
  • Audio Conferencing through PSTN
  • Contact Search

What are the Lync features which don’t working during a WAN outage in the branch office?

  • Inter-site Data (IM, App Sharing, etc.)
  • Conferencing (IM, Video and Web)
  • Presence & DND based routing
  • Modify Presence or Change Call Forwarding Settings
  • Contact List
  • Response Group and Call Park

Who are the SBA partners available for Lync Server 2010?

  • AudioCodes
  • HP
  • Dialogic
  • NET
  • Ferrari

How do I deploy a SBA?

I put together a summary of the required steps. For more specific details visit here.

  • Pre-create a computer account (for the SBA) in the branch office.
  • SBA is added to the Lync Server 2010 Topology via Topology designer. These are the only steps which had to happen before the SBA can be deployed in the branch.
  • SBA gets dropped from the vendor to the branch with preinstalled software. The local administrator connects to the device via webinterface and configure the IP address, so that the SBA is reachable and he connects the SBA to the domain. After the IP configuration the ISDN connection to the PBX has to happen.
  • SBA receives the configuration information from the centralized store. Now the certificates had to be assigned to the SBA, afterwards the administrator can start the services.
  • Lync Server 2010 administrator moves the User from the local pool to the SBA.

How can I provide redundant Response Group Service with Lync if my primary datacenter fails?

If you stretch your Lync pool across datacenters you can accommodate this.