I've only seen extension 1502 do it so far. That leads me to think it's something funny just with that extension. I guess I will try deleting and re-adding it. PR5 seems stable and certainly fixed a bunch of surprising problems that cropped up with 6.0. The day after our first controller went to 6.0 I was on this forum posting about the loopstart buzzing. I didn't find out about the DTMF dialing issue later because it would occur at such random times.