Hi I am new here so please be gentle if this is a stupid question or has a simple answer......
Having just purchased a used iphone 3g, which I now was in full working order at purchase, I had it unlocked so as to be able to use it with my current sim etc.
It had a broken screen which I have replaced, following the instructions step by step online, everthing works apart from one thing, I can only here anything by pressing onto the speaker button, ie if I hold the phone to my ear I hear nothing, if I press the speaker button the sound comes through fine, bnut obviously ever other person around me can also hear my conversation.
I have rechecked numerous times the connections 1, 2 and 3 inside the iphone and all seem to be fully connected.
Mate I've never looked inside of an iPhone so your already way ahead of me..... if the speaker is connected via ribbon cable it's possible the ribbon cable is damaged, without testing equipment you can't rule out hardware failure on the basis it was ok before!
It's also possible this is a software issue so before you spend money I would suggest a restore as it can help to rule out a software issue but if it is software related it may not resolve the problem!!!