OMTP CTIA adapter for increased compatibility. Suitable for converting various versions of TRRS 3.5 mm audio plugs to achieve compatibility between the CTIA standard and the OMTP standard. The function of this cable, adapter includes switching the ground and microphone in the 4pin 3.5 mm plug to resolve compatibility issues. For example, if you buy a new mobile phone and connect, for instance, a microphone, but no voice sound is heard, this may indicate that the 3.5 mm plug is not compatible with the phone. This adapter will solve this problem.