iPhone 3GS with rapid battery drain
I have the same problem; iPhone 3GS with rapid battery drain.
Got a new battery, followed all the instructions, reconnected everything and voila, no sound from the earpiece.
Some resolutions I tried from looking round the net are to try inserting and wobbling about an earphone jack that has worked for some people, tried doing a full factory reset which has shown success for some, taken the *#$^ thing apart several times to the point I can do it blindfolded now but still a no go with the internal ear speaker. Everything else seems to be okay though.
I called my carrier and they said to take it into one of their stores and they'd send it off for inspection but most likely I'd get a 4s as a replacement under my insurance but will be without a phone for 20 or so days... not an option.
I'm hanging for the iPhone 5 so what I'll do is have to take calls on the speakerphone which works or via bluetooth headset... the iPhone 5 is rumoured to be out June/July so will only have to put up with it a couple of months or so till I upgrade.
If anyone susses out an easy fix please let me know.
Is this a good question?