By default Nimbus supports internal Service to Service transfers without further requirements. For Attendant Console users a Service Transfer does not visually differ from any Blind Transfer or Safe Transfer. However, special restrictions and behaviors apply.

Transfer Limitations

(warning) Please note that some of these limitations are currently by Microsoft Teams client design and may not be improved via Attendant Console updates:

In the following, let's assume a simple scenario where Nimbus Service A acting as receptionist desk, forwarding calls to a Nimbus Service B.

  • A "Safe" transfer will merely check for service B's existence. There is no automated check on service availability, opening hours, or any other means to guarantee that the transferred call will be handled.
    → As long as the Service B has a workflow to accept the call the task is considered as "handled" from Service A perspective.
    (lightbulb) Make sure to check the presence status of the Service prior to a transfer to check if it is working within Opening Hours and has available users to handle the transfer.
  • For PSTN transfers the following limitations apply:
    • A call transferred to PSTN number will be ringing for 2 minutes (e.g. if Target ignores the incoming call). There is currently no possibility for you to cancel from Attendant Console UI.
    • PSTN licensing restrictions apply for any transfer type → See note below.

      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.

Reporting Outcomes

Assuming the same Service A to B scenario above, the following Power BI related outcomes apply:

  • For each Service a separate service session is created respectively for reporting.
  • Both sessions are combined in a unified / user session (customer journey).

The Nimbus Reporting Model outcomes :

Task Result SuccessfulNot Successful
User SessionService Task Transferred InternalService Task Accepted
Service SessionUser Internal Transfer SuccessUser Accepted