On Sun, 12 Jan 2014 18:34:29 -0800 in sci.electronics.repair, Jeff
Liebermann <
je...@cruzio.com> wrote,
>On Mon, 13 Jan 2014 02:05:38 +0000 (UTC),
>
vjp...@at.BioStrategist.dot.dot.com wrote:
>
>>I got an Iphone headset which has four contacs on a phone plug.
>>But the phone uses a normal 3-contact universal handsfree.
>
>Slightly wrong. A 3 contact 3.5mm plug can be used for earphones
>only, but if you want a microphone, you'll need the 4th connection
>(nearest the plug).
But the OP is talking about a 3 contact 2.5mm plug (see subject
line) for a mono headset with a microphone, total three wires.
>>I have bought numerous adaptors but they don't seem to work.
>>I can hear the phone, but I can't be heard.
The four conductor 3.5mm plugs are wired two different ways.
Using the wrong one often produces those symptoms.
If you split a 3-contact plug to add a 4th contact for a mic, there
are two ways to do it. The obvious way is to keep the ground on the
sleeve contact where it's always been and use the second ring
contact for the mic. That's the way phone manufactures did it, and
standardized under the OMTP Open Mobile Telecom Platform.
http://en.wikipedia.org/wiki/Open_Mobile_Terminal_Platform
Then some jerkwads produced something called the iPhone and just had
to be different. They put the ground on the second ring and the mic
on the sleeve and called it their own standard under the CTIA
Cellular Telecommunications Internet Assholes.
http://en.wikipedia.org/wiki/CTIA_-_The_Wireless_Association
Regrettably, most manufacturers decided to switch rather than fight,
so most new phones follow the CTIA wiring. A simple adapter
crossing ring2 with sleeve is all it takes to convert either one to
the other.
http://handtokey.blogspot.com/2013/11/converting-omtp-headphone-to-standard.html
http://www.amazon.com/Sony-EC250-Headphones-Adaptor-1249-0456/dp/B009HW15UG
https://encrypted.google.com/search?q=omtp+ctia