SNS3, whilst I thank you for your efforts, you have slightly missed the point of my question - unless you are using a handheld unit, with simple direct to headset interface, but I don't think you are??!!
As repeatedly stated, some of them are, some of them aren't. I don't know the model number, and am not in the airplane to look it up. Fortunately, they give us a few days off, every few blue moons and again.
Perhaps, SNS3, if you knew what you were talking about, you could answer the question instead of changing the subject You and DFC should get married.
No subject was changed. You simply provided incorrect information, and are unhappy that more than one poster called you on it.