I'm looking for some pointers to information in an attempt to do something that may seem a bit impossible at first. I'm attempting to build an adapter that converts from 2.5mm audio to what is commonly known as RJ11 (the kind that would plug into a phone, like 4p2c or something similiar).
In order to do this, I need to track down the electrical specifications for rj11 jacks in the United States. All I've come across so far are some references to various off-hook, on-hook, and ring voltages. However, I haven't found anything detailed enough that would allow me to build such an adapter.
Before someone tells me that such a things cannot be done, Motorola used to sell something a while back call "The Cellular Connection Interface". One website mentioning it is this:Now, the device I'd like to built isn't exactly like this one (since it seems to use some proprietary way of getting a dial-tone out of the cell phone). However, it is similiar.
connect the audio and mic part of the 2.5mm adapter to form the tip/ring signal and then the mutual ground of the 2.5mm becomes the negative line. All of this is somehow hooked up to a 9v battery and a transformer to get the right voltage on the line. Then, I plug one end of this contraption into my cellphone and the other end into a regular phone. I place a call on the cell phone, and then I should be able to pick up the regular phone's handset and speak. Viola. Any idea how I'd go about doing such a thing or where I can find information detailing the electrical requirements of the rj11 jack?
Any help is much appreciated. Also, if anyone knows of a more appropriate newsgroup on which to post this message, please let me know.