If the ground wire of the headphone line and the microphone line are opposite, this will cause this situation. So the phone is identified through this key switch.

1. The solution is to just pull out the headphone plug a little, don't insert it completely, and adjust the plug. If that doesn't work, you can only go to a repair shop to change the position of the ground wire and microphone line.

2.OMTP is the 3.5mm interface standard for headphones with MIC. It is usually called the national standard and is used by the country. The pin connection method is (from the small end): left channel-right channel-microphone-ground wire.

3. There is also a 3.5mm interface for headphones with MIC that is an international standard, called CTIA. The pin connection is: left channel-right channel-ground wire-microphone.