You can use an adapter
To connect to the iPhone headphones with a thick plug, you can purchase a special adapter from Belkin. However, this adapter has two obvious drawbacks. First, it does not support the microphone function, and secondly, it is not flexible, and so will stick out of your phone, and it's not very nice and convenient.
Another adaptor is manufactured by the company Apple. These problems it has, but costs about $ 20. So think for yourself, do you tolerate the inconvenience or to opt for the more expensive product.
Use the adapter
The company Shure is releasing a special adapter for the iPhone (full name - Shure Music Phone Adapter for iPhone). Adapter is not cheap – as much as $ 40, however, solves all the problems with the use of headphones for the iPhone.
Use a soldering iron
This method is suitable only for those who are skillful with a soldering iron and definitely confident in their technical skills. You can just solder the headphone to the headset of the iPhone, which is included in the kit. Network you can even find a video with detailed instruction.
In General, the easiest way is to spend money and buy specialized headphones. This will protect you from all sorts of problems and unpleasant situations.