I have a Helixnet system on V2.0 , when I connect my Beyer 5pin headset I have no audio , if a connect a CC400-X5 headset it works , both headsets are wired the same 
I connect a 5 pin – dual ear headset(one ear wired to pin 4, the other to pin 5) – to the HBP-2XS. -> All is good. I connect a 5 pin – single ear headset(one ear wired to pin 5, the other is not terminated) – to the HBP-2XS. -> No audio and the mic does not feedthe PL. I connect a 5 pin – single ear headset(one ear wired to pin 4, the other is not terminated) – to the HBP-2XS. -> All is good.
Headsets are Beyer Dynamic DT108 /DT109.BP are correctly configured for 5 pin inthe hidden menu.
Solution:the headset detect mechanism in the beltpack looks for aresistive load on the left headset output because on Clear-Com headsets a singleear headset uses the left only and a dual ear uses both.   If someone buys a 5 pin beltpack and wires their single ear headset touse just the right ear (pin 5) then the beltpack (and any main station orpanel) that they plug it in to will think there is no headset plugged in. 
there is a Headset Sense Bypass“Feature” in Helixnet beltpack (in 2.0 as well as 3.0) that can be enabled by: -   Press and hold Beltpack Menu button for 5 seconds, youwill enter the “Advanced” menu.-   Scroll down and select “HS sense bypass”-         Select Enabled 
This will bypass the headset detection mechanism. This setting is lost when you Reset to Default.