I have the Samsung Galaxy S4 Active with AT&T. I have missed several calls on a daily basis as I don't always hear it ring. I have the volume turned up all the way that the apps will allow. This is driving me crazy. In call volume is fine and using the earbuds is fine as well, so I just don't understand why the ringer volume when turned up is so low. Is this just my phone or is anyone having the same issue and how can I resolve it? I am way past my 15 days to send it back to replace with a different phone. :-( Please help if you can. Thank you.