Best Basic Telephone Recording Interface Circuit To Build ?

[Artifex]

Hello,

A friend asked me where they could buy a telephone recording interface to use to connect their landline to their digital voice recorder. I immediately thought of the good old Radio Shack 43-2208. But to my shock, I discovered that Radio Shack no longer sells it; one of many useful products they discontinued.

Searching around the net, most of the offerings are very overpriced digital recorders with an interface built in or interfaces for pc's via usb.

Thankfully, there are still some circuits posted on the web.
I found these two websites...

http://www.sagebrush.com/phontech.htm

http://www.epanorama.net/documents/telecom/teleinterface.html#audioint

Between the two sites there are approximately 10 basic circuits and several more advanced circuits.
My friend does not need a circuit for a recording studio or a broadcast studio,
just a circuit that will yield relatively even volume levels for both the local and distant call participants.

Could you folks take a look at these circuits and give me a little guidance as to which one to build,
before I start looking for parts on MCM, Newark, Arrow, Digikey, and Jameco's websites.

TIA

 

[hevans1944]

I thought 'phone phreaking ended when cell phones became widely available.

 

[whateverls15]

I thought 'phone phreaking ended when cell phones became widely available.

And me, i dont even know that such thing exist

 

[hevans1944]

And me, i dont even know that such thing exist

In the previous century, in the United States of America, telephone service was a monopoly controlled by Bell Telephone, somewhat affectionately also called Ma Bell. The technology used for telephones originated from a wholly-owned Bell subsidiary, Western Electric. Both companies tightly controlled any and all information concerning how the telephone system worked. This policy led of course to the creation of a group of people who were determined to learn and publish the details of the inner workings of the telephone system. Such people acquired the pejorative nick-name telephone freaks, shortened to 'phone phreaks by the practitioners themselves. I won't go into any details about how the 'phone phreaks accomplished their mission, but they were very successful and full details of how the telephone system worked in the 1950s to 1970s era are now readily available on the Internet.

Early exchange of information was by means of peer-to-peer bulletin boards (BBS) hosted on small computers with dial-up modems, as well as self-published "underground" papers passed hand-to-hand, and eventually open publications like TAP. Usually only one user at a time was supported on a BBS because each simultaneous user needed a telephone line with a modem connection to a host computer that supported a multi-tasking operating system. At the time this was happening, DTMF signaling was exploding across the USA as everyone who had a teen-aged daughter wanted a Princess telephone with a keypad instead of a rotary dial. Some adults, such as myself, used Princess telephones too. I liked the lighted dial... er, touch pad.

The phreaking community quickly discovered that there were more DTMF combinations than provided on a standard telephone keypad, said extra combinations being used by Ma Bell to route telephone connections. With a small portable DTMF generator (a so-called Blue Box) command DTMF sequences could be injected during a telephone connection to obtain free, but illegal, long distance telephone connections. In the same era, Ma Bell lost a major law suit regarding the connection of "foreign" equipment to their telephone lines. This court decision opened up the telephone system, allowing almost anyone to connect almost anything to the telephone network. 'Phone Phreaks had a real holiday with this for quite some time.

With the coming of cellular telephone service, and "free" long distance calling from many providers of same, the motive for 'phone phreaking diminished. Nevertheless, it apparently still exists and you can read about here.