It might happen that you can listen to the music playback from your mobile phone, but you are not able to use the microphone during a call. Here is why:
There are 2 common types of 3.5 mm connector for mobile headsets in the market
First type, microphone connection is made through Ring #1 * The second type, microphone connection is made through the Sleeve The picture below shows the location of Ring #1 and the Sleeve on a connector.
If you can listen to music but are not able to use the microphone on a call, it could be due to that only the Tip and Ring #1 are connected properly. No matter your headset is type 1 or type 2, please make sure the connector is fully inserted to the jack on your mobile phone. In some cases where the mobile phone is covered with a protective case, special note has to be taken to fully insert the connector of the headset into the jack. If the opening for the connection jack on the case is small, you may need to remove the protective case before connecting the headset to the mobile phone. If the headphone connector is already inserted fully but the problem persists, contact Philips Consumer Care for further assistance.