How to modify your Sony headphones extension cable (1 meter) so that you can use it with iPhone.
Craft knife (or any other type of small, sharp knife)
A little bit of time
Strong glue (optional)
File (emri board or anything like that will do)
1. Get your craft knife and start carefully cutting away at the black connector bit that goes into the jack. You should start to expose some grey plastic. Completely remove the black part so there is a grey square.
2. Start filing the corners of the grey square (to check which corners, put the headphones into your iPhone and try to turn the connector, the headphones pop out because of the 2 corners. Once you have filed away a decent amount, put the headphones into the jack and start to slowly turn it around, the iPhone jack housing is sharp enough to file it down for you!
3. (OPTIONAL BUT RECOMMENDED) Put a tiny bit of glue around where the wire goes in. This saves the wire from being pulled out (just in case precaution).
All done! Took me about 10 minutes and I was experimenting! All works PERFECT now!
Edit: You could also use a black marker (permanent) and color in the grey bit so the look is consistent. Go aesthetic!