Voice issue while calling

[OscarMaDi]

Hi there!
I've been having a lot of issues with the 720 lately... Bought one last month, but there was a gap between the glass and the body so I sent it back (took a month to replace it...).
Today arrived the new one, and it looks just gorgeous, I've been playing all day long, syncing accounts and downloading some apps/games, but then, few hours ago I recived a call, answered and then realized that the other person couldn't hear me. I tried almost every place near me (house, car, garden, street) but nothing, I can hear the other people talking during the call but they just can't hear me. Later I tried switching my SIM with another one (different OEM) but the result was the same. It's kinda strange 'cause I can use the voice commands or even call through Skype and in these ocasions the phone recognize my voice perfectly, so definitely, it's not a mic problem.
I've contacted Nokia support via twitter immediately and their solution was simple: "Nokia care". I bet this'll be the most effective, but I just can't handle loosing my phone for another month...
Do you have any ideas? I thought the noise suppression microphone could be involved.
Thank you!

 

[rdubmu]

I had something similar happen to me on my titan 2, make sure the microphone on the bottom isn't plugged with lint. Be gentle and use a paperclip or something.

 

[OscarMaDi]

Thanks for your reply rdubmu. I discarted the lint because it's a brand new phone and the mic works fine while using voice commands or recording a video. It's just during a call (regular call, skype or viber, doesn't matter), that they can't hear me so I still think it's due to a noise suppression microphone problem. Yesterday I tried to use the earphones and their mic, and it works fine, I had a normal conversation.
Today I went to a Nokia Care and the guy told me it was a strange case and he reinstalled all the software (through navifirm, I guess), but after that, the problem persisted. I left the phone there until tomorrow and if he doesn't find a solution he'll send it to the SAT.
I've read on some blogs that it was a common issue on the iPhone 4 and all of them got their phones replaced.
Now I'm wondering how do you manage to open the unibody lumia 720 to acces to the internat parts (as I know, on the bottom of the 920 you can find two holes for that purpose, but the 720 doesn't have such thing).
I'll explain how this is going in the coming days.