Newsgroups: rec.audio.tech
Subject: Re: Convert audio output to RJ-11?
References:     
[email protected] (Mike Gnitecki) writes:

> "r.crowley"  wrote in message news:...
> > Note that RJ-11 is the connection between the telephone instrument and the
> > wall socket .
> > You seem to be asking for an interface to the handset. Is that correct?
> > This is a  bit more tricky. Is acoustic coupling (holding the recorder to
> > the phone mic) not working properly?
> 
> Sorry, I guess I had the terminology wrong. I had thought that RJ-11
> was the name for a telephone-type cable, no matter what it connected
> between.

There are different kinds modulat of telephone:

RJ-11 is RJ style "wall" connector 6 position 
         6 pin , 4 pin, and 2 pin plug ends
RJ-22 is RJ style "handset" connector 4 position 4 pin plug ends
RJ-45 and RJ-48 are RJ style "network" connector 8 position 8 pins.

> Yes, you're correct -- I'm looking for an interface to the handset.
> Acoustic coupling would work, but it'd be inconvenient (who wants to
> manually hold a device for 30-second intervals throughout the day?).
> It'd be easier if the digital voice recorder could simply directly
> connect. I'd love to be able to simply unplug the receiver and plug in
> the digital recorder, but I don't know how practical / inexpensive
> this is. I got the impression, from talking to another group member
> via email, that it's neither easy nor cheap. But I'd appreciate any
> ideas.

There are some adapter boxes which adapt the handset connector 
signals to the other sources. This kind of adapters are sometimes
used with video converenging systems and early IP phone systems.
I have also seen some small handset (RJ-22) connector to recorder
adapters sold in some shops.

Basically the four wire RJ-22 handset has two wire pairs. One
has the signal going to the speaker in the handset. This is
generally connected to spaker directly. The other wire has 
the signal connected to microphone (electret or carbon) 
in the handset more or less directly. Thhe actual specifications
what level signal travel on those wires, so generally some testing
is needed to do the connection. Generally if you connect a
high impedance isolation transformer to such wire pair through a
capacitor (one such circuit for spaker and another for microphone part)
you can get the audio sound in and out of the telephone.

An introduction to telephone interfacing can be found at
http://www.epanorama.net/circuits/teleinterface.html
(it briefly touches this topic also).

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/