In Nimbus, DTMF (Dual-Tone Multi-Frequency) is primarily used in Workflow Activities (e.g. "Input Customer" to route calls according to the choice made by the incoming caller). Based on the direction, we can distinguish between:
- Inbound DTMF: With Inbound DTMF, Workflow Activities capture the DTMF inputs provided by the callers.
- Outbound DTMF: In rare scenarios there might be a need for sending outbound DTMF tones from the Nimbus user accepting the call, towards the caller (e.g. to open a door).
This article explains in which scenarios DTMF tones are available in Nimbus calls and in which scenarios they are not.
Inbound DTMF
Inbound DTMF (from the caller to Nimbus) is always available during a call1, except in very specific scenarios in which Microsoft disables the DMTF tones for the remaining life of the call. The following diagram visualizes when DTMF tones are available and in which scenarios they get disabled:
1Although DTMF tones can be sent at any time during a call by the caller, DTMF inputs are only interpreted by Nimbus in case the call reaches an activity in the workflow which is expecting those.
Based on the above diagram, if a Nimbus call gets transferred from the main service to another Nimbus service and gets to a user in one of the subsequent services, DTMF tones will not be available anymore for the entire duration of the call. In such case, workflow activities requiring DTMF tones will behave as follows in case a user transfers the call via Attendant Console to another Nimbus service:
- Input Customer and Input Customer (Advanced): The prompt text of the IVR is skipped and the NR exit of the IVR is taken.
- Collect Information: The prompt text is skipped and the No Input exit is taken.
- Standby Duty: Standby Duty functionality is not negatively affected by the limitation as in that case a new outbound call is started towards the standby duty user in which DTMF tones work as expected.
Possible Workarounds
- Workaround 1: Transfer the call via Teams client to the service having an IVR. In such case, the call after the transfer will be a new Nimbus call in which DTMF tones are available again.
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Workaround 2 (only applies when using Direct Routing): Transfer the call via AC to the phone number of the Nimbus service. In order to make this work, Reverse Number Lookup (RNL) has to be disabled for the target Nimbus service’s Resource Account's Phone Number Assignment first.
💡 RNL can be disabled by executing the following Teams PowerShell command: Set-CsPhoneNumberAssignment -PhoneNumber <phone number assigned to the target Nimbus service’s resource account> -ReverseNumberLookup SkipInternalVoip
🤔 Why is Microsoft disabling the DTMF tones?
Due to privacy reasons, Microsoft disables the DTMF tones in case more than 2 participants are in the call. In the above mentioned scenario, for a short time, following three participants are in the call:
- The customer calling the Nimbus service
- The user accepting the Nimbus call
- A guest user that needs to be in the call for a short time (until a user accepts the call) to make sure the user accepting the call can see the names of the subsequent Nimbus services (instead of the name of the main Nimbus service the customer called) in the Teams toast.
🔎 See Conversation Handling Activities for more information on the above mentioned workflow activities.
Outbound DTMF
Outbound DTMF is limited to a few Queue Distribution Types only, as shown in the following table:
| Distribution Type | DTMF from Nimbus user to caller |
|---|---|
| Broadcast | ❌ |
| Direct | ✅ |
| Direct Conference | ❌ |
| Pickup Conference | ❌ |
| Pickup with adjustable RONA | ✅ |
If for example a Nimbus call is distributed to a Nimbus user via a Queue having Direct Conference configured as the distribution type, the Nimbus user won't be able to send DTMF tones towards the caller.