I'm trying to get some Plantronics/Poly headsets to work with the 6900 series phones. The headsets work by means of passing audio to the headset, but they won't operate the hook switch. I have a Plantronics CS520 with the APU-76 and a 6940. Plantronics says this is the correct cable for compatality, but I don't see the CS520 listed on the official Mitel list, only the CS540. I've also tried the Voyager 5200 UC with the cable and it functioned the same as the CS520. Audio worked just fine, but couldn't control the hook switch. I tried to pair the headset to the phone directly but after pairing it to the phone it wouldn't actually connect. It kept failing when trying to connect.
Does anyone have any recommendations with the Plantronics/Poly headsets and the 6900 phones? We have quite a bit of Poly headsets and I'd like to get these fully functional if possible.