Attendant - Service Transfer

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

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

Safe transfer
  • Will merely check for Service B's existence. As long as the Service B has a workflow to accept the call the task is considered as "handled" from Service A perspective.
  • There is no automated check on Service availability, Opening Hours, or any other means to guarantee that the transferred call will be handled.

→ We recommend using "Blind Transferin a Service to Service transfer scenario. Make sure to check the presence status of the receiving Service to ensure users are available to handle the call.

PSTN transfers
  • 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.


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.


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  Successful Not Successful
User Session Service Task Transferred Internal Service Task Accepted
Service Session User Internal Transfer Success User Accepted

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