Have you set the Volume controls under settings ? Please understand, that there are different volumes for Media vs. Phone calls. Make sure to increase the correct one.
Secondly, can you try the phone without the headphone ? Is the volume ok that way ? If you are using bluetooth, understand that it has its own volume control. One more consideration is that, some earphones have their own volume controls. See if that can help.
Last edited by Perseus; 2nd June 2014 at 11:47 AM.