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".
PRECONDITIONS
- Enterprise Routing Contact Center Outbound Calls are an Enterprise Routing and Contact Center Service Type feature. "Outbound Conversations" must be enabled via Modalities 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:
- Navigate to the My Overview, Services Overview 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 preconditions above). - To start the outbound conversation, click on the Call icon .
☝ Note: User Presence, Nimbus Status and UI interactions
MS Teams Presence:
- 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.
Nimbus-specific interactions:
- Contact Center When users are in persistent RONA or in (extended) After-Call Work time, Outbound Service Calls are not possible.
- Any blocking Nimbus User States will also disable the call button, e.g. when there is an incoming/connected call or other blocking tasks such as ACW.
- Call On Behalf sessions are subject to Dashboard Supervision, meaning that a Supervisor can listen, whisper or barge-into an existing session.
Known Limitations
INC Outbound Task Limitations
KNOWN OUTBOUND TASK LIMITATIONS
General Outbound Call & Task limitations
Audio Modality:
-
Audio delay for outbound PSTN and UPN calls: There is a possibility for latency after establishing an Outbound Call between Agent and Customers. The delay is caused by Microsoft infrastructure and outside of Nimbus control. In order to minimize latency, an optimized approach was implemented and can be enabled by Luware Support 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.
Specific Call Features:
- Federated outbound calls are not supported. Any of “Outbound” type Flow Actions will return an error
- Preferred user routing is currently not supported for outbound calls. Preferred users specified will be ignored and the task will be distributed according to the configured Distribution Policy.
Specific: Outbound Call with Workflows
☝Please note that “General Task limitations above may also apply.
-
Supported Workflow Activities: Currently, all workflow activities except the following are supported in Outbound Calls with Workflows:
- “Voice Message”
Nimbus Design Notes
- Internal O365 User Search for Outbound Calls: The “Outbound Call” dial pad in Nimbus also allows to search for internal Nimbus 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.
- Reporting visibility of terminated Outbound Calls: Terminated Outbound Calls are currently not reflected on any reporting view (Reporting, Dashboard, or Power BI). This is currently by design as (repeatedly / manually) started or scheduled Outgoing Calls could affect and skew service KPIs.
- Nimbus Power BI Template: While the data related to Outbound with Workflow flows through seamlessly to the template, data related to Outbound Call with Workflow may appear in Service Overview > Inbound Calls widget in the template. Future releases will see improvements to this.
INC Transfer to PSTN Limitation
☝Nimbus and related addons can only perform PSTN transfers according to Microsoft's licensing and constraints.
✅ As Administrator you need to acquire Microsoft Teams phone licenses
🤔Which PSTN licenses do I need to acquire?
Service Licensing
|
Target Service using any of the Microsoft | PSTN Connectivity options ▼ |
Licence to apply for Nimbus Services |
| Direct Routing |
“Teams Phone Resource Account” 🔎 See: |
| Calling Plan |
“Teams Phone Resource Account” license, plus
🔎 See: Microsoft Learn | Microsoft Teams Calling Plans 1 Only required for Outbound Call functionality, also see “Ahead notice Pay-as-you-go Calling Plan licensing changes” below. |
|
Operator Connect |
“Teams Phone Resource Account” |
User Licensing
| Target User | License to apply to Nimbus Users & Call Targets |
|
All Users, including … + Agents that handle Nimbus calls + Attendant Console transfer and consultation targets. |
“Teams Phone Standard”, each account having: |
☝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.
🤔How does PSTN licensing affect Service and call transfers?
Assuming that the initially called Service has (no) PSTN license assigned - the following scenarios may unfold:
Scenario A - Service A has a PSTN license. Transfers to other Services occur.
⮑ The PSTN license carries over throughout transfers to other Nimbus Services B and C.
⮑ As the license carries over, a PSTN transfer to an external target is possible from either Service.
Scenario B - Service B has no PSTN license. A Transfer to Service C occurs which has a PSTN license.
⮑ The customer skips over Service A and manages to reach Service B instead.
⮑ The PSTN license is missing on Service B, so nothing is carried over to Service C.
⮑ Even if Service C has its own PSTN license, a PSTN transfer to an external target is not possible.
🌟Learnings:
- Nimbus will use the PSTN license – and create a (transfer) Session – from the FIRST Service responding to a call.
- Regardless of how many internal Service transfers are performed thereafter, the FIRST Service PSTN license remains in effect.
- If a PSTN license is missing, the transfer task will fail and be treated accordingly by the System.1
- Even if a Service being transferred towards has a PSTN license, it cannot be added in post, as the Call Session is already ongoing from the first-responding Service.
✅ For your licensing needs this means: If you require PSTN transfer functionality, you'll need to ensure that this Service is handling all your incoming calls.
- For ONE first-level / Front Desk Service, you'll need a PSTN license for this particular Service.
- For MULTIPLE first-level Services scenario, you'll need PSTN licenses for all first-level Services.
1🔎 Assumption: Workflow takes the normal “Exit” Announcement route and Service Session will conclude with a “Transfer failed” outcome. For more details on analyzing your Reporting results, refer to Nimbus Reporting and Static Dimensions > "Service Session Outcomes"
☝Note that handling and tracking of running cost for PSTN licenses is outside of the Luware support scope. If you however require assistance in extending and/or configuring your Nimbus Services for PSTN, our support will gladly assist you:
Luware Support Address
| Luware Website | https://luware.com/support/ |
|---|---|
| Luware Helpdesk | https://helpdesk.luware.cloud |
| Cloud Service Status | https://status.luware.cloud/ |
INC PSTN License Check Enforcement Notice
☝Ahead Notice: Microsoft enforcing PSTN license checks for bot calls
Amendment 07.05.2025: Microsoft has moved the date from June to end of September.
From: https://devblogs.microsoft.com/microsoft365dev/enforcement-of-license-checks-for-pstn-bot-calls/
🔍 What’s changing?
Effective September 30, 2025:
- Teams users will still have the option to transfer calls to other Teams users manually even if they don’t have a PSTN phone system license.
- Bot-initiated transfers and add participant requests to non-phone system enabled users will be blocked.
🤔How does this affect Nimbus?
Nimbus uses bots to initiate and monitor (safe) transfers and create call conferences. If Microsoft decides to pull through with this change by September 30, 2025, all Nimbus transfers and consultation calls will be blocked and fail without any possible workaround or error handling.
Topic: Microsoft announced changes to PSTN license checks for bots. From the Blog Post of Microsoft:
As part of Microsoft’s feature parity with Teams Phone extensibility, we’re announcing the enforcement of Phone System license checks for Bot-initiated transfers to Teams users. This current gap in our systems will be addressed in September 2025.
Microsoft Teams requires that Teams users behind applications such as queue applications require a phone system license and the user to be Enterprise Voice Enabled. We’re aligning the Microsoft Graph API with that requirement.
What is the change?
Effective September 30, 2025:
- Teams users will still have the option to transfer calls to other Teams users manually even if they don’t have a PSTN phone system license.
- Bot-initiated transfers and add participant requests to non-phone system enabled users will be blocked.
🧭 What is the Impact for Luware Nimbus Users?
- Transfers Within Nimbus: Transfers to users without a Teams Phone license will no longer work. This includes internal transfers between agents or service users.
- Supervision Features: Supervisors must have a Teams Phone license to monitor or intervene in calls. Without it, supervision capabilities are disabled.
- Workflow Transfers: Any transfer initiated from a Nimbus workflow to a user lacking the appropriate license will fail. This disrupts automated routing logic and impacts service continuity.
- Attendant Console Transfers: Transfers via the Attendant Console to unlicensed users are blocked. This affects manual call handling and redirection.
✅ What you need to do
✅To ensure uninterrupted service:
This change mandates the use of a PSTN License on all Users you either transfer to or start a consultation call with.
- Audit User Licenses: Verify that all users involved in call handling, transfers, and supervision have the Microsoft Teams Phone license assigned.
- Update Workflows: Adjust workflows to route calls only to licensed users. This includes adjusting any Distribution Policies and Agent Service Settings for Agents with the according skills and responsibilities.
- Train Supervisors: Ensure supervisors understand the licensing requirements and have the necessary access.
- Monitor License Status: Implement checks or alerts to identify users without valid licenses.
☝Ahead Notice: Microsoft licensing changes
Amendment 03.09.2025: Added Operator Connect as affected customer base. Added clarification that Direct Routing customers are not affected.
Microsoft Licensing Change: What Nimbus Customers Need to Know About Calling Plan and Operator Connect Changes.
🔍 What’s changing?
Effective November 1, 2025:
- Microsoft will enforce a significant licensing change that directly impacts how outbound PSTN calls are handled in Microsoft Teams—especially for services like Call Queues (CQ) and Auto Attendants (AA).
- This change affects all organizations using Microsoft Calling Plans for telephony and it might affect organizations using Operator Connect.
-
The change has direct implications for Luware Nimbus customers in the following scenarios:
- When using Outbound Call functionality, including Call On Behalf.
- When using the Attendant Console for transfers to PSTN numbers.
- When doing Workflow Transfers to PSTN numbers.
🔍 What’s not affected?
- There is no change for Direct Routing phone numbers.
🔍 You will find the full announcement on the MSFT Learn page, specifically “Changes to licensing required for Auto attendant and Call queue outbound PSTN calling”. Excerpt quoted below - important parts highlighted:
Calling Plan
Starting November 1, 2025, a Pay-As-You-Go license will be required for Teams Voice Applications (Call Queues and Auto Attendants) Resource Accounts that use Calling Plan numbers for outbound PSTN calls.
The following scenarios will require a Pay-As-You-Go license:
- Outbound PSTN calls made by Teams Call Queue agents on behalf of a Resource Account
- Outbound PSTN calls made by Auto Attendants or Call Queues
- Callback PSTN calls initiated from Teams Call Queue or Teams Auto Attendant
- On-behalf-of calls made via Graph API and Phone System Extensibility
If Pay-As-You-Go licenses aren't assigned to the relevant Call Queue or Auto Attendant Resource Accounts by November 1, 2025, outbound calls will fail.
Operator Connect
On November 1, 2025, the following outbound calling scenarios may no longer be available depending on your carrier/operator:
- Outbound PSTN calls made by Teams Call Queue agents on behalf of a Resource Account
- Outbound PSTN calls made by Auto Attendants or Call Queues
- Callback PSTN calls initiated from Teams Call Queue or Teams Auto Attendant
- On-behalf-of calls made via Graph API and Phone System Extensibility
Coordinate with your carrier/operator to ensure you continue to have uninterrupted service for these on-behalf-of outbound PSTN call scenarios. If the appropriate arrangements aren't made with your carrier/operator, then outbound calls made by agents on behalf of resource accounts, by auto attendants or call queues or via the Graph API and Phone System Extensibility will fail.
Your carrier/operator provides the details on what adjustments may be required.
🤔How does this affect Nimbus?
Nimbus uses bots to initiate and monitor conferences well as monitor and report any Outbound Call calls and Call On Behalf of a Nimbus Service. Any transfer scenario also requires the Nimbus bot to take calls back safely.
This includes:
- CQ agents making calls on behalf of a Resource Account (RA)
- Callback scenarios configured in Call Queues
- Auto Attendants transferring calls externally
- Calls initiated via Graph API or Phone System extensibility
🧭 What is the Impact for Luware Nimbus Users?
For customers using Microsoft Telephony exclusively and leveraging Call On Behalf features via Luware Nimbus, this change means:
- You must replace existing Calling Plan / Operator connect licenses on resource accounts with Pay-As-You-Go licenses.
- Failure to do so will result in service interruptions for Outbound Calls initiated by Nimbus services, e.g. within either Attendant Console, Workflows in Contact Center routing.
- As highlighted in internal discussions with Microsoft, this enforcement aims to curb misuse but inadvertently affects legitimate use cases like those supported by Luware Nimbus.
✅ What you need to do
✅To ensure uninterrupted service: We urgently recommend for Customers begin transitioning to Pay-As-You-Go licenses well before November 1st to avoid last-minute disruptions.
- Review all resource accounts configured for outbound PSTN calls.
- Assign Pay-As-You-Go calling plan licenses to these accounts via the Microsoft 365 Admin Center.
- Validate license coverage for all users and services involved in call transfers.
- Consider setting up Communication Credits to fund Pay-As-You-Go usage if needed.
📞 Need Help?
If you’re unsure how this change affects your setup or need assistance updating your licensing, please reach out to your Luware Customer Success Manager or contact our Support Team.
INC Luware Support Address
| Luware Website | https://luware.com/support/ |
|---|---|
| Luware Helpdesk | https://helpdesk.luware.cloud |
| Cloud Service Status | https://status.luware.cloud/ |