People can't hear me but I can hear them on iPhone4

Apple products are generally perceived to be of a high standard and quality. However, this does not mean that it can not have few gliches
One of the common issue is that some people with iPhone 4 have issues with mic.
The problem is that when you make calls,  you can hear the recipient perfectly well but they seem not to hear you at all or you have to shout with speaker phone activated before they can hear you.
The funniest part is that the voice recorder works fine and whenever you make calls with Skype, Jumble etc, people can hear you perfectly.
This means that  there is nothing wrong with the mic of the phone.
The problem lie in the codec chip located on the logic board of the iPhone4.
You will need to open up the phone to fix this issue.

To fix it, follow the links provide below
Link 1 : http://www.ifixit.com/Teardown/iPhone+4+Teardown/3130/1
This Link will teach you how to open up your phone completely 

Link 2: http://www.beijingiphonerepair.com/fix/diy-repair-iphone-4-people-cant-hear-me-i-cant-hear-other-people/
Link 2  will show you what you need to do in other to fix the problem.

Remember you will need to buy set of tools and make sure you follow all the instructions given in the links.

In case you have cold feet in opening up your device, i can offer to solve the problem for you.

Thanks for reading. Hope this helps