Du2

I've been hearing an infrequent "beep" coming from my dashboard area which seems to only happen when my CD player is on and only when I'm in the city versus never in the country. Today, I was braking at a "smart" traffic light - the kind with all the video surveillance stuff and antennas - and I heard a loud 'beep' and my CD player turned itself off and then flashed the letters 'ST TRAF'. What the heck is this all about? Is it because Toyota uses the 900 MHz frequency for its operation just as the smart grid devices use for their control?