This a wierd one. I have a GT-I5800 running Froyo. If I try to make, or receive calls, the microphone does not work (i.e. the other person cannot hear what I am saying). However, if I turn speaker phone on, then they can hear me! This leads me to believe its a software, rather than hardware issue. I have tried, without luck, to search for a solution to this, and have even considered a custom ROM, but have no idea as to which one would be best, I have also performed a factory reset to see if that would fix things, but it didn't (although I do have a much tidier phone now!). Does anyone have any solutions/suggestions to this? If it involves a custom ROM, then that's fine (although I haven't ever done that before, so a step by step would be very helpful!). It is very frustrating, epecially as my wife's phone (same make, model, firmware), is working with issue! Thanks.