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Attendant - Service Transfer

New Design for Attendant Console

This page describes both Attendant Console 1.0 and the new 2.0 redesign. You can change between designs right within your settings.

💡 Note: For more recently onboarded Nimbus customers, this choice might be disabled and you will be using the 2.0 design by default.

 

Attendant Console 2.0

Attendant Console 2.0 - 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.

🔎 Related concepts: The steps below refer to UI elements and concepts explained on the Attendant Console main page.

 

Transfer Scenarios

Let's assume a simple scenario where Nimbus Service A is acting as receptionist desk, forwarding calls to a Nimbus Service B.

Scenario
Outcome
Safe transfer
  • Will merely check for Service B's existence. As long as Service B has a workflow to accept the call, the task is considered as "handled" from Service A's 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 Transfer" in a service-to-service transfer scenario. Make sure to check the presence status of the receiving service to ensure that users are available to handle the call.
PSTN transfers
  • A call transferred to a PSTN number will be ringing for 2 minutes (e.g. if the target ignores the incoming call). There is currently no possibility for you to cancel this from within the Attendant Console UI.
Context Transfer (of Parameters)

Please note that in all Transfer scenarios general limitations apply. These are listed in the following.

Transfer Limitations

INC Transfer Limitation List

💡In the following we list all known Transfer limitations, either by design or external circumstances.

 

Context Handover during Transfers

INC Context Handover Limitations

The Transfer of Custom Context Parameters works within Attendant Console. Currently Supported Scenarios are:

Transfer 
to User 
to Service

By User on 

✅ Call Data + Customer.Custom Fields 
and 
System Data.

⬜/✅ Custom Context Parameters only if enabled in respective Service Settings.

✅All Call Data + Custom Fields, 

System Data and 
Custom Context Parameter 

get transferred.
By Service
 ❌ No Context gets transferred.1

✅All Call Data + Custom Fields, 

System Data and 
Custom Context Parameter 

get transferred.

CONTEXT TRANSFER LIMITATIONS

The following Context Transfer limitations are known. We are actively working to improve this in a future update.

  • 1 Workflows > “Transfer” Workflow Activity: A Custom Context Transfer from within a Service workflow to any target will not work.
  • 2 No Transfer out of Conferences: All MS Teams Conference calls - e.g. those created during Consultation via Attendant - do not support transfers, which also prevents Context Parameters from being handed over.
    → If you require Context to be transferred, use Blind Transfer or Safe Transfer scenarios respectively.
 
 
 

Transfers and RONA State

INC Transfers and RONA State

✅ Note: Only applies if “Persistent RONA” is enabled via Distribution Service Settings.

  • When the target User is already is in RONA state.
    ⼑ A message will be shown after a transfer attempt is made: “Transfer cannot be started to a User, who is in a Nimbus Task”. There will be no User Session for Nimbus Reporting.2
  • When the target User ignores / doesn't answer the transfer (e.g. Timeout), Nimbus will not flag users with RONA state1.
    ⼑ User Session in Nimbus Reporting marked “Cancelled”2
  • When the target User actively declines a transfer will also not flag users with RONA state. 
    ⼑ User Session in Nimbus Reporting marked as “Declined”.2

1đŸ€” Why is RONA not applied in this the case? There is no persistent RONA state if User has not been selected by the Nimbus Task Queue and Distribution. 

2 Depending on the Attendant Console transfer scenario (safe/blind), the call will return to the initial User or be lost. This is not related to RONA behavior.

 
 

Transfer to Teams Auto Attendant and Call Queues

INC Transfer to Teams Auto Attendant and Call Queues Limitation

☝Transfers towards the UPNs of Teams-native Auto Attendants’ or Call Queues’ Resource Accounts will fail. Based on the PSTN connectivity option used, transfers towards the Resource Accounts' assigned phone numbers will work as summarized in the table below.

Transfer Type Direct Routing Calling Plan Operator Connect
Attendant - Safe Transfer  🛠 ❌ ❌
Attendant - Blind Transfer  ✅ ✅ ✅
Attendant - Consultation Call  🛠 ❌ ❌

Workflow Conversation Handling Activities  > Transfer > “Leave Nimbus”  disabled

 🛠 ❌ ❌

Workflow Conversation Handling Activities  > Transfer > “Leave Nimbus”  enabled

 ✅ ✅ ✅

đŸ€” Why are transfers failing? Is there a workaround?

🔎Analysis: This is caused by Microsoft Teams limitations on what voice applications (such as Call Queues, Auto Attendants, and Nimbus) are allowed to do. This cannot be circumvented by Nimbus.

🛠 Workaround: For these transfer types to work, Reverse Number Lookup (RNL) has to be disabled in the Resource Account's Phone Number Assignment. RNL can be disabled by executing the following Teams PowerShell command:

Set-CsPhoneNumberAssignment -PhoneNumber <phone number assigned to the CQ/AA resource account> -ReverseNumberLookup SkipInternalVoip

⼑ After disabling RNL for a Phone Number Assignment, Teams will automatically forward the call to the Direct Routing SBC, which then needs to redirect it toward the Resource Account of the Call Queue or Auto Attendant.

 
 
 
 

Transfer to PSTN Licensing and Limitations

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.

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/ 

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.  

đŸ€”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.

✅Required Action for Tenant Administrators / Service Owners:  This change mandates the use of a PSTN License on all Users you either transfer to or start a consultation call with.

đŸ€”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: https://learn.microsoft.com/en-us/microsoftteams/teams-add-on-licensing/virtual-user

 
 

đŸ€”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.

⼑ The PSTN license carries over throughout transfers to other Nimbus Services B and C.
⼑ 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.

⼑ The customer skips over Service A and manages to reach Service B instead.
⼑ The PSTN license is missing on Service B, so nothing is carried over to Service C.
⼑ Even if Service C has its own PSTN license, a PSTN transfer to an external target is not possible.

Scenarios A and B: PSTN Licensing and transfer outcomes in case of different Services being called

🌟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/
Luware support contact details
 
 

Transfers and Nimbus Reporting Outcomes

INC Transfers and Nimbus Reporting Outcomes

🔎Rule: Last Outcome

 Rule for Nimbus Reporting > Outcomes & Sessions List Task Results:  The overall Service Session outcome in a “Transferred-by-user Scenario” is set according to the outcome of the last User Session.

 
Transfer Scenario User A - Session 1 Outcome User B - Session 2 Outcome Expected Service Session Reporting Outcome1
User A blind / safe transfers to Internal Destination B, which accepts Transferred Internally Accepted User Internal Transfer Successful
User A blind3 transfers to Internal Destination B, which does not respond (ignore) Internal Transfer Failed Cancelled User Internal Transfer Failed
User A safe4 transfers to Internal Destination B, which rejects, Customer terminates afterwards. Accepted Declined User Accepted
User A transfers to Destination B Voicemail 2,5 directly Transferred Internally None, as no User Session is created for user B.2 User Internal Transfer Successful

1 See Nimbus Reporting Model >  Static Dimensions > “User Session Outcomes”

2 Voicemail and Reporting: Any direct "Transfer to Voicemail" Actions via Attendant Console are not creating a new User Session or any related User State checks for the Nimbus Reporting Model.

3 Blind Transfer behavior: When the destination doesn't accept – and has Voicemail or any other forwarding activity enabled – the transfer will not reach Voicemail nor the forwarding target. This is expected Contact center behavior and avoids the loss of calls.

4 Safe Transfer / Voicemail behavior: When the destination doesn't accept - and has Voicemail enabled - the transfer will NOT reach the Voicemail. This is expected Contact Center behavior to avoid a potential call loss. 

5 Disabled Voicemail: Nimbus cannot check ahead if voicemail is enabled for a user, but the “Transfer to Voicemail” UI element is always shown. Also refer to the “Transfer to disabled Voicemail” limitations.

 
 

Transfers to disabled Voicemail

INC Voicemail Limitations

☝KNOWN LIMITATION: Currently, there is no way to check ahead if a (target) user has voicemail features enabled. This is a design limitation by Microsoft which Nimbus currently cannot circumvent. 

Voicemail Redirect Setting in MS Teams

Additionally, the voicemail feature may also be deactivated as part of a tenant-wide IT policy by your administrator. There are also known cases where Microsoft accepts transfers to voicemail but the recipient has no means to check (e.g. MS Teams Client / License restrictions). We highly recommend using this feature only in case voicemail is enabled for the Microsoft Teams user.

 
 
 
 

Attendant Console 1.0

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.

Scenario
Outcome
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 Transfer" in 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.

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? 

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: 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.

LEARNINGS

  • 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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