Some uncertified Skype for Business audio devices do not behave correctly when used with the HDX RealTime Optimization Pack. Users might require a way to selectively allow or disallow audio devices from passing through to Skype for Business as human interface devices (HIDs).

Example of what can cause the issue: When users connect certain headset devices to a client endpoint with the RealTime Media Engine, a dial tone might play when you open Skype for Business. In this example, the end users have the Plantronics Savi 720 device connected to a Cisco IP phone, and then to a thin client device. The Savi 720 device base has three modes:

• Compute
• Mobile phone
• Desk phone mode

The end user selects the Computer button on the base and hears a dial tone automatically when Skype for Business opens. Using several unsupported devices can cause issues for Skype for Business and the RealTime Optimization Pack. The Optimization Pack version 2.8 or later resolves this problem by allowing you to disable or blacklist the device so it’s not used as a composite device. Instead, this device is passed to Skype as another audio device or non-composite device, with no support of HID button actions.

Starting with the HDX RealTime Optimization Pack version 2.8, the Realtime Media Engine supplies a way for you to selectively blacklist and whitelist peripherals on the VID: PID level. To do so, find out the correct VID:PID for the HID that you want the RealTime Media Engine to ignore. Once you’ve specified the HID to ignore, that setting works on all RealTime Media Engine platforms: Windows, Linux, Mac, RPi. Functional.

To ignore a specific human interface device, add the following registry string value on the server:
HKEY_CURRENT_USER\SOFTWARE\Citrix\HDXRTConnector\MediaEngine
Name: BlacklistedHID
Value format: VID1:PID1;VID2:PID2
Example: 047f:02f7

Example Scenario:
In this scenario, we’re using a Plantronics Savi 720 device. To blacklist this device so it’s not passed to Skype for Business as a composite device, follow these steps:

1. To locate the VID, connect the headset to any Windows endpoint. In this example, the VID1:PID1;VID2:PID2 is 047f:02f7

2. To ignore the specific human interface device, add this registry string value on server:
   
   HKEY_CURRENT_USER\SOFTWARE\Citrix\HDXRTConnector\MediaEngine
   Name: BlacklistedHID
   Value format: VID1:PID1;VID2:PID2
   For example: 047f:02f7

3. To confirm that you made the change, view the Optimization Pack MediaEngine log.
4. In the Optimization Pack logs, confirm the device is listed with the correct product ID and blacklist states it’s skipping – Current log location - C:\Users\XYZ\AppData\Local\Temp\Citrix\HDXRTConnector\MediaEngine.Net.20190327.135321175.
   In this example, the line displaying device (047f:02f7 - <USB device path>) is blacklisted in the registry. Skipping… shows that it’s been done.

5. Open Skype for Business and confirm that the SAVI-720 is running as Other Device.

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Problem Cause

Using several unsupported devices can cause issues for Skype for Business and the RealTime Optimization Pack. The Optimization Pack version 2.8 or later resolves this problem by allowing you to disable or blacklist the device so it’s not used as a composite device. Instead, this device is passed to Skype as another audio device or non-composite device, with no support of HID button actions.

Limitation
Ignoring a Human Interface Device leads to disabled handling of the HID button on the device.
An audio device with a disabled HID appear in the Skype for Business UI as a non-headset because the HID part is ignored. The user can use the device for receiving or making audio or video calls.