I don't think this was always this way.
Whenever I go into ATT Navigator, my Plantronics 520 makes a "call answer or initiated" sound (3 beeps) and it sounds like it is "off hook" (like there is air time) for about 10 seconds. Then it goes silent and starts again after 10 seconds. As soon as I exit navigator it stops.
During this time, if I get a call or make a call it works properly.
Please help. It is making me crazy.