Attendant - Blind Transfer

The quickest scenario when using Nimbus is the blind (unattended) call transfer. The starting point of this scenario is a queue with at least one incoming call getting assigned via the Stratus queue distribution system.

The Steps below refer to UI areas and concepts explained on the Attendant Console main page.



Call Accept

✅ Precondition: Caller is shown within the Incoming Call Queue. Once assigned to you the call is shown as "Incoming" in the Conversation Controls and your Teams Client is be showing the "ringing" call popup.

You accept the call. 
→ The caller is transferred to your Conversation Controls, shown as "Active"  
→ You are now connected to the caller.  
→ The "Attendant State " widget in the User Interface area shifts to "Working " / "Conversation Active" to signal that you are handling a call for your service team.

💡 From here on you may put the caller on hold or end the call using the controls in the Conversation Hub.

Contact Search

Within the Contact Search you can now search for a contact by typing any identifying element (clear name, SIP-address, telephone number). 

💡 Use common constructs in the search such as @domain to find multiple fitting results. 
💡 You can also type a E.164 standard telephone number in the search box (+ country code) (subscriber number) to forward to that target 
💡 You may want to use filters to narrow down large lists of results.

Quick Actions - Blind Transfer

  1. Select a contact entry and click "Blind Transfer" within the Quick Actions to forward the call.
  2. Select an available transfer target. You can pick a transfer target in the pop-up (UPN, Voicemail, PSTN numbers

→ You will end the session with a blind transfer. The scenario may unfold as follows:

 Contact accepts the call

  1. Your contact will be called (ringing) directly.
  2. Assuming the call is taken:
    1. ... via call: The calling customer is now directly shown to the blind transfer call recipient. Your contact should now be shown as "BIC" = "Busy In Call" accordingly, verifying a successful transfer.  
  3. ... via voicemail: if voicemail is configured for your recipient, your caller should be directly transferred to the caller's voicemail box and hear the corresponding announcement. No further action is required on your behalf.
  4. The caller is removed from your Conversation Hub and you are ready to take the next call.

 Contact doesn't respond or rejects

  1. Any unsuccessful blind transfer will not be returned to you. 
  2. The call is marked as failed in the reporting model. ( User Internal Transfer Failed )

KNOWN LIMITATION Currently there is no way to check ahead if a (target) user has voicemail features enabled. This is a design limitation by Microsoft which Nimbus currently cannot circumvent. Additionally the voicemail feature may also be deactivated as tenant-wide IT policy by your administrator. There are also known cases where Microsoft accepts transfers to voicemail but the recipient has no means to check (e.g. MS Teams Client / License restrictions). → We highly recommend using this feature only in case voicemail is enabled for the Microsoft Teams user.

After the Call

  • As soon as you finished the blind transfer the attendant "Attendant State " in the top area of the User Interface shifts back to "Active" (green)"  
  • You're free to take on the next call → Step 1.

Notes on Call Transfers

  • Blind transfers will not be returned to you directly, but may be handled otherwise. You will not necessarily receive the same customer again.
  • A Blind Transfer that is not taken or hung up by the customer results in a "failed" task in the Nimbus reporting model.



Out-of-the-box, Nimbus and affiliated addons can only perform PSTN transfers according to Microsoft's licensing and constraints.

Which PSTN license do I need to acquire?

As a tenant administrator you need to acquire the following licenses and assign them to the application instance of the respective Nimbus SOURCE service (team) that will act as PSTN transferor:

Your Setup Required License
Direct Routing "Microsoft Teams Phone Resource Account"
Calling Plan "Microsoft Teams Phone Resource Account"
+ "Microsoft Teams Domestic Calling Plan" or "Microsoft Teams Domestic and International Calling Plan" or "Microsoft Teams Calling Plan pay-as-you-go"+ "Communication Credits" (if these aren't already included as part of your plan)
Operator Connect "Microsoft Teams Phone Resource Account"

☝ As of 2023 "Microsoft Teams Phone Standard" licences are no longer supported by Microsoft. Previously those licenses were viable for Nimbus. → Regardless if you are using Direct Routing, Calling Plans, Operator Connect - the "Microsoft Teams Phone Resource Account" license is now always required

☝ Please note that Luware staff cannot make recommendations on which license plan is best suited for your needs. Depending on your scenario, additional Teams App licenses may be required. Exact details are to be discussed with your Microsoft contacts.

🔍 Also see:


How does PSTN licensing affect Service and Call Transfers?

Assuming that Service A has a PSTN license assigned - but further Services don't - the following scenario may unfold:


  • Scenario A - Service A workflow is configured to transfer the caller to Service B. The license of Service A is used, the PSTN transfer occurs. The PSTN license is re-used throughout further transfers to Services C..D...x.
  • Scenario B - Service B is called directly instead. Now the workflow of Service B attempts a redirect to either service A or transfer to C. The PSTN transfer fails due to a missing license on Service B.


  • For one first-level-response Service: If you handle first-response calls always via the same Service you need a PSTN license for that particular first-level Service.
  • For multiple first-level-response Services: If you handle first-response calls always via multiple Services you need a PSTN license for all those first-level Services .
  • Nimbus will attempt to use the PSTN license of the first service that responded to a call, regardless of how many further internal service transfers are performed thereafter.
  • If no PSTN license is found on a service that requires it for a transfer, the transfer task will be considered as failed and be treated as such by the system (e.g. workflow exit announcement, reporting "transfer failed" outcome).

☝ Note that handling and tracking of running cost for PSTN licenses is outside of Luware support scope.
If you require assistance in extending and/or configuring your Nimbus services for PSTN our support will gladly assist you:

🔍 Refer to the external reference: Microsoft Teams PSTN connectivity options and Microsoft Teams add-on licenses.


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