Vintage phone handset for softphone?

[NorthernElectric]

I've been working on getting asterisk up and running for the last couple of days.  I thought I had a working system already from a few years ago.  I had set one up as an answering machine with an outgoing message beginning with the SIT out of service tone to fool telemarketers' autodialers.  I was just using an old Motorola modem as a generic X100P fxo hooked up to my POTS.  I don't recall exactly why I shelved it but I must have used the hard drive out of it for something else, so had to start from square one again.  Anyway, I now have asterisk running on FreeBSD 10.1 up to the point where I can dial in and run the demo over my POTS line or over my LAN with microSIP on my Windows box.  Now to get to work on a dialplan.

Now that I have some old phones (and will likely get more), I thought something like this would be useful for testing them offline so to speak.  I bought a used tdm400p with an fxo module on it.  I plan to start off by getting one fxs module for experimenting, and if it works out, fill the card with 2 more.  In order to be able to call the phone connected to the fxs port while I only have one fxs module, I will use microSIP.

So I finally get to the point of this post.  What I had in mind was using a vintage phone handset for audio input and output to/from microSIP.  I was even thinking that maybe a dial-less D1 base would be perfect as I could turn the receiver on and off with the hookswitch so that if I had the audio plugged in to the headphone jack, audio output would switch back to my PC speakers when the phone was on hook.

Has anyone tried something like this and if so, how did it turn out?

Would transmitter and receiver impedances be suitable for a direct connection to PC microphone and headphone jacks?

[dsk]

This page are place to start:
http://www.epanorama.net/circuits/teleinterface.html#hybrid
I did experiment with this some years ago and it never turned out to well. 
Today I use a linksys adapter and a dialgizmo, its worth the money!

dsk