Microphone noise problem, iPhone 4 gsm

Hello from Croatia. My name is Tomislav Gavran.

I have microphone noise problem on my iphone 4 gsm. when people talk to me, they hear noise similar to speaker interference when you are making calls. This is happening only during phone calls, not on internet calls such as viber or skype.

I know that there are mic problems with iphone 4 and that there is solution for that. I did the same thing as guy in this video

http://www.youtube.com/watch?v=0jhWxYTVx...

this thing worked for a while and now problem is back. I did some tests to see where is the problem. I tried severe things. Applying pressure on this part

http://imageshack.us/a/img338/2445/74be9...

helped, noise stopped, but now this doesn't help neither,

But when I put my fingers on this place on both sides of the phone, noise stops

http://imageshack.us/a/img542/4265/iphon...

Could you tell me where the problem is? I saw on your web page that changing dock connector can solve problem of mic noise so I would like to try that.

Thanks in advance, I apologoize if my English is bad.

Greetings from Zagreb

Update: everything is working fine right now, now I'm waiting for iphone to go crazy again:)