Is this a new device? If so and the issue has been there since the beginning then you need to take it to a local VZW or Apple store as it may be a warranty issue and they will replace your device. If this is a phone you have had and the issue just suddenly started then it's possible that you have water damage (much easier than you may think...rain, condensation from being in a humid place like a hot car or in the bathroom while showering). It could also still be a warranty issue...you would need to have it looked at to find out...but if there is any chance that it is water damage then it will not be replaced unless you have paid for a warranty that covers accidental damage. You can also try the usual troubleshooting techniques to see if they help. Reset, Restart, Restore.