Works all cable boxes. Voice control only works with X1 or Xfinity Flex set-top boxes.

How to.. Pair your remote with your set-top box to use voice control.
Press and hold the Setup button (about 3 seconds) until the Status LED changes from red to green.
Press the XFINITY button.
Follow the on-screen instructions to enter your 3-digit code. Once the code is accepted, pairing is complete.

The voice remote (XR11v3) from XFINITY is a remote control that allows XFINITY on the X1 Entertainment Operating System customers to find what they want faster by using voice commands to change channels, search for shows, get recommendations and more. Customers can use their voice to quickly find their favorite content, tune to channels, search and control their DVR. Benefits include:

Voice control
Backlit keypad
Aim Anywhere feature
Easy access to accessibility features like Closed Captioning and voice guidance
TV input control
Originally supplied with models: X1 Series, XG1, Xi3