These days I am doing almost all my shopping online – mainly on Amazon. And why not – they offer great discounts, unbeatable offers and everything is done comfortably relaxing in your couch. So when I needed a headphone for my smartphone, I went online and bought an affordable Philips headphone. It arrived in just one day, but when I plugged it in, my Android phone threw up an error – “Your earphones are not compatible with the phone. Please try another ones”. This was something I had not seen before. So went online and a quick search revealed that there are two different types of earphones/headphones available – one is called OMTP and the other type is called AHJ or CTIA.
OMTP earphones differ from AHJ earphones only in the manner the wiring is connected to the 3.5mm jack. Even in the wiring the only difference is between the ground and the microphone pins. The OMTP 3.5mm jack has the ground pin connected to the sheath while in the AHJ configuration, the sheath has the microphone pin connected. This means that by simply swapping the ground and the microphone wires inside the headphone, you can switch the headphone between the OMTP and AHJ standards.
Fixing through an OMTP to CTIA/AHJ adapter
There are many adapter cables available in the market that make use of this simple trick. You connect your headphone to one end of the adapter and the other end of the adapter cable goes into your smartphone. The adapter cable internally swaps the ground and microphone pins effectively switching between the OMTP and AHJ standards. This is easier and very effective method.
Fixing permanently using a soldering iron
If you are an electronics enthusiast, then perhaps you would want to open up the headphone cable and solder the joints to swap the ground and microphone pins. All smartphone headphones have a joint in the middle where microphone is located. You have to pry it open gently and then you will find a micro push button switch. One one side the switch the microphone is connected and on other side the microphone wire and the ground wire coming from the 3.5mm jack. You have to un-solder the ground and microphone wires from this switch, swap them and solder it back.
Conclusion: If you bought the wrong type of earphones/headphones, then you may have to buy an OMTP to CTIA/AHJ standard adapter. You can also manually rewire the headphone cable to change its standards.