[AusNOG] Hybrid Audio Controller

[Peter J. Cherny]

On 02/23/15 17:30, Ben Hohnke wrote:
> Handset to handpeice is normally just raw audio. You can techinically
> crimp on 2 x 3.5mm audio jack and plug it into a normal mic port, and
> you'll have the audio in and out feeds.

Not advise that should be acted on !

At worst, you need transformer isolation,
at best a purpose build interface.
The radio world solved these issues at least 75 years ago.

Maybe just google "telephone hybrid balanced"
inter-alia www.tbu-ip.com for a modern solution.