The most basic scenario when using Nimbus is the safe (attended) 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

(tick) 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.

(lightbulb) 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). 

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

Quick Actions - Safe Transfer

Select a contact entry and press "Safe Transfer" within the Quick Actions to forward the call.

(lightbulb) You remain part of the session while an attended transfer is in progress. During this phase you are unable to handle other calls. The scenario may unfold as follows:

Contact accepts the call

  1. Your caller will be put into a conference call with wait music playing. To you the call is shown as "Parked"  in the conversation Hub
  2. In the meantime your contact will be called (ringing).
  3. Assuming the call is taken:
    → your contact should now be shown as "BIC" = "Busy In Call" accordingly, verifying a successful transfer.
  4. The caller is removed from the "Park" position in your Conversation Hub and you are ready to take the next caller

Contact doesn't respond or rejects

  1. The caller is returned to you. Calling you will be retried until either the caller hangs up or you take the returning call back.
  2. You can simply retry the transfer or try other options:
    1. Use other quick actions in your Contact Search and try reaching your contact target via Email or Chat.
    2. Search for a substitute contact and try any action there.

After the Call

  • When you end the call your "Attendant State " in the top area of the User Interface shifts back to "Active" (green)" 
  • If a call was successfully transferred to a contact target the search field is cleared automatically to show your default favorites and popular contacts. 
  • You're free to take on the next call → Step 1.

Notes on Call Transfers

  • By default, a rejected call transfer will be returned to you after a certain time (RONA).
  • Attended transfers will in your conversation hub until taken. You are not available for other conversations until the caller task is resolved.
  • A safe transfer returning to you that is not taken or hung up by the customer results in a "failed" task in the reporting model. (User External Transfer Failed & User Internal Transfer Failed)


Static RONA timeout

RONA time for a safe transfer cannot be configured within Nimbus at the moment, since ongoing conference invitations cannot be canceled. Until Microsoft allows for an ongoing conference cancellation invitation the RONA timeout is set to 30 seconds default.

Transfer to PSTN Limitation

Out of box Nimbus and affiliated addons can only perform PSTN transfers according to Microsoft services licensing & constraints.

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

Your SetupRequired License
Hybrid with DR Trunks"Microsoft 365 E1/E3" + "Phone System" 
"Microsoft 365 E5"
(Phone System is already included)
Hybrid with Calling plans"Phone System - Virtual User"
+ Domestic
(and optionally international) calling license

Online Only

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).

(warning) 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:

You can reach us via the following means: 

(info) Refer to the external reference: Microsoft Teams add-on licenses.