Shared Line Appearance (SLA) in Skype for Business (with busy on busy)

Very often we as MVP are asked about the Busy-On-Busy feature missing Skype for Business.

The native feature for every single device, user or other client is not yet available.
And I can't make any announcement until today if this is planned or not.

But what I can introduce is the Share Line Appearance, yes here Busy-On-Busy is available. Making S4B more look like an old fashion PBX :)

What it the Share Line Appearance.
This is a new feature introduced with the actual firmware from Polycom VVX and last Skype for Business Update November 2015.

Shared Line Appearance (SLA) enables you to configure a group of multiple devices that can each answer calls to a shared phone number (extension).
(SLA it is not supported for Skype for Business clients on computers, mobile phones, or other devices):

What does this mean to us. Well we can use busy on busy only within the VVX configured groups. But not yet between devices and client, or between soft clients.

The supported device are:
  • Polycom VVX300 with firmware update 5.4.1
  • Polycom VVX400 with firmware update 5.4.1
  • Polycom VVX500 with firmware update 5.4.1
  • Polycom VVX600 with firmware update 5.4.1
A rouge description can be found here:

The most interesting features could this:
  • Busy on Busy – excess calls are automatically rejected with a busy signal.
  • Call Forward Busy – excess calls are routed to an alternative number that's configured for the workgroup.
  • Voicemail on Busy - excess calls are automatically forwarded to Voicemail.

  • Installation:

    It needs to be installed as an Server Application based on the Pool Servers and SBA/SBS.

    New-CsServerApplication -Identity 'Service:Registrar:%FQDN%/SharedLineAppearance' -Uri  -Critical $false -Enabled $true -Priority (Get-CsServerApplication -Identity 'Service:Registrar:%FQDN%/UserServices').Priority
    Stop-CsWindowsService RTCSRV
    Start-CsWindowsService RTCSRV

    where %FQDN% is the fully qualified domain name of the pool or server.  

    Create and configure a SLA GROUP:

    First we need to create a group and assign members, as well as set the MaxNumber of Call, which will trigger the busy single once the call count is exceeded.

    Set-CsSlaConfiguration -Identity SLA_OFFICE1 -MaxNumberOfCalls 4 -BusyOption BusyOnBusy
    Add-CsSlaDelegates -Identity SLA-OFFICE1-Delegate 

    Configure an SLA BUSY GROUP:

    if no busy signal is required, instead you can forward the call.

    Set-CsSlaConfiguration -Identity SLA_OFFICE1 -BusyOption Forward -Target tel:+49891234567

    Configure an SLA MISS CALLED OPTION:

    you can also decide what actually will be done if a call isn't answered:
    you can either FORWARD, set a busy signal BUSYSIGNAL, or DISCONNECT the caller.

    Set-CsSlaConfiguration -Identity SLAGroup1 -MissedCallOption Forward -MissedCallForwardTarget

    Summary of the feature list (MSFT):

    • All delegates in the group can answer inbound calls to the same shared number. The calls can be PSTN-based or SIP-based.
    • Delegates can hold and pick up calls.
    • Delegates can transfer calls to a number outside of the SLA group.
    • Delegates can see how many calls are currently on the shared number, and view the status of each of those calls.
    • You can configure a maximum number of concurrent calls for the shared number. You can also set how you want additional calls to be handled after this maximum is reached. Excess calls can be rejected with a busy signal, forwarded to an alternate number, or forwarded to voice mail.
    • You can configure how you want missed calls (calls not picked up after a certain time) to be handled. If you enable voice mail for the group identity, missed calls automatically go to voice mail. If you do not have voice mail enabled for the group identity (shared number), you can choose for missed calls to be rejected with a busy signal, forwarded to an alternate number, or disconnected.


    1. SLA..hmm.. how unfortunate acronym.. will love to debate with PMs about SLA, when after couple of minutes it will turn out what he means by SLA is different from what I mean about SLA. Wasnt there any other 3-letter acronym available???

      1. :) Hi Ricardo generally you are right. But you might simply not use the short cut SLA. Im not using SLA in this direction with customers how will get confused

    2. Hello,

      there is no such version as VVX 5.4.1 on the polycom site:

      So is this some feature planned for the distant future, or still in private beta?

      1. Hi Ricardo,

        you are right, the 5.4.1 VVX version should be released this month. so you might need to wait a little longer.

    3. Just added as QUICK COMMEND...

      The -IDENITIY parameter is not a SLA Group Idnentifier. it is a USER !!!
      So you can't configure dedicated group and join users here.

      Idenitity (for all cmd-lets are) defined as: Microsoft.Rtc.Management.AD.UserIdParameter

    4. do someone know how to change the delay before the call is running through the missedcall routing option ? It seems it's 20 secs but can't be changed


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