TRS to RJ9 audio conversion.

I was wondering if anyone had resources that I could reference for creating a TRS (Tip-Ring-Sleeve) 1/8" audio, to RJ9 Telephony jack conversion kit.

Effectively, I'm trying to create a bridge from an audio device (PC/MP3 player) to a telephone connection, allowing audio from the PC/MP3 player to be broadcast into a telephone line.

Trying to maintain the Keep-It-Simple-Stupid method here, so if something involves using prefabricated devices like a computer (as in a software driven method), I'm probably not going to be able to use it.

Thanks in advance

Interesting... first time I hear RJ9. For me it was RJ22, [4p4c] but well,

The level to inject signal into the telco has to be a few millivolts ! And unsure if that way it will introduce lots of noise if one of the pins is grounded.
If the telephone apparatus is not electronic, the signal level to inject should be about 0.2V rms measured on the line, limited to 3KHz.
Broadcasting into a single telephone line would not be much broadcasting, would be transmitting.

If you have that TRS signal truly floating balanced monophonic, do not use the shield (sleeve)
If it is stereo, tip and ring would have to be joined and sleeve would be used.

Somehow I remember microphone being the outer pair and earphone the inner pair.
Miguel

I should elaborate, I am an amateur when it comes to hardware. Perhaps I've used some inaccurate references.

The 4P4C connector (popularly, though incorrectly, called RJ22, RJ10, or RJ9), is the de facto industry standard for wired telephone handsets. It is used to provide connection from the base of the telephone to the handset. -Wikipedia

The specific reason I'm looking to create this, is because my job (call center oriented) now calls that we leave a tightly scripted and long winded message on peoples answering machines. Except for the beginning it is very general, and one could easily get away with using a recording.

I want to create said recording, store it on my MP3 player (iPod), and be capable of playing it when neccessary (very often), hence the need to be able to have my iPod connected to the phone line (also, using a phone line splitter, so I can still talk if neccessary)

Does anyone know of good further readings on this, or the procedure of building such a device? (simplicity is crucial)

Simplifying,

Male 2.5mm to Male RJ9 Adapter | 1-800-Headsets

Should work if your player is floating (not connected to a battery charger at the moment of use). The volume output of the player should be set low enough to get the same level as 'normal' clear, undistorted speech.

Miguel