DA75 does not provide audio to headset with PTT

[ph-issues-again]

We work in a sensitive room that requires the use of push-to-talk equipment. We recently purchased a large batch of Poly HW520 headsets with quick disconnect ends, the Poly SSP1051-03 Push-to-talk QD adapter, and Poly A10-16 RJ-9 to QD adapters for POTS phone use (and they have worked properly).  We additionally purchased DA75 USB to QD adapters so we can use the same headset and PTT combo for computer calling as well. This does not work properly. No audio is passed from the computer to the headset unless the PTT button is depressed - which makes this unusable. That is, we cannot listen without having the talk button pressed. Some rudimentary investigation shows that sound is passed from the computer to the headset speakers when the USB is first plugged in (if all QD's are connected first and PTT is not pressed) but as soon as the PTT button is pressed and released the audio to the headset is cut off and only returns when the PTT is held. The headset and DA75 combo work properly when the PTT module is removed.  We cannot utilize specialized software like the Plantronics Hub or Manager Pro in our call environment but an isolated one-off test with Hub shows the DA75 firmware is up to date and reports Setid: v.1.1160.65.2025 and usb: v.2025. This was tested on a multiple Win 10 computers and on a Linux computer with identical results.

1. Is this expected behavior?
2. If this is a firmware bug what is the timeline for getting it fixed?
3. Do all Poly USB to QD adapters have the same issue? (DA40/45/50/55/70/80/85/etc.)
4. If the DA75 is not going to be fixed, how will Poly/HP remedy the issue?

See Poly Articles 000030479, 000026986

[SteffenBaierUK]

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[ph-issues-again · Accepted solution]

To update: 

Contacted support and was told that the PTT module is supposed to allow you to completely disconnect from a conversation (hearing and talking) so a radio dispatcher, for example, could trade between separate conversations and that it wasn't made to be used to disconnect the mic only - which, i'm pretty sure, is incorrect.   At least, that's not how it operates when used with 'analog' devices.  I was also told that he PTT is not compatible with any DA audio processor which seems to contradict the previous statement of operation - it's either working properly or it's not.

In the end, it seems to me that Poly tried to make the audio processor 'smart' and in doing so broke compatibility with some QD components.  That is, i believe a feature of the DA is to put someone on hold when you disconnect the QD and the DA's seem to treat the PTT mic disconnect as a full QD disconnect.

Regardless, i got the boot and am SOL.  Hope this will be useful to someone