Call On Behalf

Outbound calls impersonating as a service

The Call on Behalf feature allows service users to impersonate and make calls as the service itself. This feature is also known as "Call As" or "Calling as a Service". 


  • Enterprise Routing Contact Center Outbound Calls are an Enterprise Routing and Contact Center Service Type feature. "Outbound Conversations" must be enabled via Modality Service Settings for the corresponding service.
  • The user must be Online in MS Teams or the “Call on Behalf” Icon will be disabled in the Nimbus UI.
  • Services using this feature need to have a PSTN number assigned in order to dial out to an external number. Otherwise only UPN (internal users and services) can  Also see the "Known limitations" section below.

🔍 Note that Basic IVR Services (User assignment type = None) are excluded from this feature.


Call on Behalf from Within the Portal UI

"Calls on Behalf" can be manually initialized from the Nimbus portal:

  1. Navigate to the My Overview, My Services or Attendant Console and click on the telephone icon next to the service you want to call on behalf as.
    ⮑ A teams dial out popup opens. You can now dial a number.    
    💡 Before calling, you can still choose between all services which are available to you (and fulfill the prerequirements above).
  2. To start the outbound conversation, click on the Call icon .
Start a “Call on Behalf” of a service via the Nimbus


  • Remember that you must be “Online” in MS Teams or the “Call on Behalf” Icon will be disabled in the Nimbus UI.
  • Being DND will not disable the button. User related "Busy Available/ Away Available" settings (made via Distribution Service Settings > Conversations Distribution) such as “available when busy” are also ignored.
  • Any blocking Nimbus User States will disable the call button, e.g. when there is an incoming/connected call or a leftover ACW task.
  • Contact Center When users are in persistent RONA or After Call Work state, then an Outbound Service Call is not possible.

Known Limitations

INC Outbound Task Limitations


  • Audio delay for outbound PSTN and UPN calls: There is a latency after establishing an outbound call between agent and customer. The delay is due to Microsoft. In order to avoid latency after call establishing, an optimized approach was implemented and can be enabled by Luware Support in Extensions Tenant Settings for your tenant.
    ☝ Note that enabling the optimized approach requires testing on your tenant as Microsoft has not yet rolled out dependent functionality globally for all MS Teams tenants.
  • PSTN Licensing: When the selected service doesn't have a phone number (PSTN license) applied, the dial pad is disabled. A dial out to a UPN (e.g. a MS Teams User or Service) is always allowed.
  • UI visibility: "Outbound Service / Call on behalf" tasks are currently only reflected in Non Personal Dashboards and Personal Dashboards. Attendant Console does not reflect these tasks, so a user won't be able to park/transfer/consult/etc.
  • Reporting visibility: Terminated outbound calls are currently not reflected on any reporting view (ReportingDashboard, or Power BI). This is currently by design as (repeatedly / manually) started or scheduled Outgoing Calls could affect and skew service KPIs.
  • Internal O365 Search: The outbound call dial pad in Nimbus allows to search for users. In order to retrieve and call to O365 contacts, a tenant admin needs to grant User.Read.All consent for all Nimbus users, as described on the Nimbus User Permissions page. 

INC Transfer to PSTN Limitation


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

Which PSTN license do I need to acquire?

As of 2023, "Microsoft Teams Phone Standard" licenses 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. 

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"

Please note that Luware staff cannot give 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…and so on.

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 treated accordingly 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 the Luware support scope. If you require assistance in extending and/or configuring your Nimbus services for PSTN, our support will gladly assist you:

Luware Support Address

 Luware Website
Luware Helpdesk 
Cloud Service Status
Luware support contact details




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