Very low volume when using Sony MDR-EX650AP

[Bunkind]

I went through two pairs of Sony MDR-EX650AP, both headset mics are super low volume and unusable, while wondering what went wrong, I found small print from the earphones' instructions "If you connect to an unsupported smartphone, the microphone of this unit may not function, or the volume level may be low". 

Can someone explain why this earphone model is incompatible with their own mobile phone? And which earphones are compatible with this phone?

[Christofer]

Hi @Bunkind, I'm sorry to hear this.

I've requested information about this. I'll let you know as soon as I know more.