Enterprise Routing Contact Center Service Type feature. Allows all users of that service to impersonate as the service during an outbound call. Also known as "Call As" or "Call On Behalf".


  • Users of this feature must be part of a Enterprise Routing or Contact Center Service.
  • The service must be enabled for "Outbound Service Call" via the "Distribution" Tab Service Settings.
  • The service needs to have a PSTN number assigned in order to dial out to an external number. → Also see "Known limitations" chapter below.

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

To initiate Outbound Service Calls:

  1. Navigate to the My Overview or My Services view and click on the telephone icon next to the service you want to call as.
  2. → A teams dial out popup opens. You can now dial a number.
    (lightbulb) Before calling you can still choose between all services which are available to you (and enabled for "Outbound Service").
  3. To start the outbound conversation, click on the "Call" icon .

Call button states and interaction

  • Nimbus interactions will disable the call button, e.g. when the user has an incoming / connected call or ACW task.
  • Offline and 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.

Known Limitations

Currently Known Limitations

  • PSTN Licensing: When the selected Service doesn't have an applied phone number, the dial pad is disabled. Dial out to a UPN is allowed. → Also refer to the "Transfer to PSTN Limitation" below.
  • UI visibility : "Outbound Service" calls are currently not shown in any UI like My Sessions or  Attendant Console - as a result user won't be able to park/transfer/consult/etc.
  • Reporting visibility: Terminated outbound calls are not reflected on any reporting view (Reporting, Dashboard or Power BI)
  • O365 Search: In order to retrieve and call to O365 contacts, a tenant admin need to grant "User.Read.All" consent for all Nimbus users, as described on the required user permissions page. We are investigating if these permissions can be reduced.

Transfer to PSTN limitation

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?

(tick) 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 SetupRequired 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"

(warning) 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

(warning) 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.

(info) Also see: https://learn.microsoft.com/en-us/microsoftteams/teams-add-on-licensing/virtual-user

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:

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