If you have a GUI pops up on screen for no reason (i.e. you have not received calls or made calls, or touched the phone at all), your extension could have been accidentally set onto a Polycom phone application which forces the GUI to popup whenever the handset is lifted.
Please find below the URL and parameters that are used by the Polycom phone causing the GUI to pop up:
Firstly you need to look for the extension number in the parameter which could be set as your extension number in the other phone. You can find out the which phone has your extension in the parameter by looking at the text log of PBX string and then look for “handset status change received from inside@domain“ which is followed by the IP address of the phone that made the GUI pop up request. You can remove your extension number after finding the IP address from the text log file.