If you are referring to the Webex Room Kit, there is currently no support in this generations hardware for a USB passthrough support. The Room Kit Mini is currently the only room series device that can utilize the USB port for a webcam.
You can connect and stream content over the top to a Room Kit / Kit Mini using devices.webex.com and the embedded WebRTC capability, but there is no SSID being broadcasted for connection.
The wireless pairing with proximity uses an ultrasound signal ...
Support for third party handsets is not likely to be added. There is consideration around these open SIP style devices, such as doorbells, intercoms, etc. but nothing currently planned.