iPhone - can't hear me ever

If this happens all the time, you may have a faulty microphone. I have used two iPhone 3Gs so far (one was returned for stuck pixels), and I haven't had any problems with the other caller hearing me.

I'm having the same problem. Others hear me fine from speakerhphone or headset but not when I use it like a regular phone. I called my work line from my iphone 3g set in speakerphone mode... when I lightly tapped the casing near the microphone (the right "speaker" at the bottom)... I could hear the normal scuffling noise you hear when tapping a microphone. I switched it off of speaker mode and it went silent. This tells me the microphone itself works fine. It must be something about that mode??? Or a hardware or software glitch?

This is my third iphone. First version got water spilled on the home button and it slowly shorted out everything. The second one decided to take a dive into the toilet. Given how much I had to pay to get my third, I have guarded it with my life. I clean it daily. I never have it anywhere close to anything that could be mistaken for moisture. It's never been dropped.

I'm not sure what it is I've been meaning to sort it out, but it started happening for me when I upgraded to the latest firmware.
Basically it works fine for about 3 minutes and then after that they cant hear me anymore, like the audio qualtiy gets worse and worse until nothing.
and it wont work on any calls after that until I reboot my phone

I called a taxi the other day because it was snowing (Vancouver) and I was on hold for 3 minutes, so I finally get through and the guys like "hello.. hello" and then hung up. !@#!@
very annoying!

plus had the phone 5 months, already two dead pixels :)

Same thing happened to me... I had to promise my fiance I would take care of this phone like it were my son and I did everything in my power to keep this phone out of harms way and of course... behold my luck... it conks out on me!

Hi,
I'm having the same problem. I can hear other people on the other end of the line but they can't hear me. However, I can hear my own voice!

I have had the phone for about 6 months and it has only just started happening. It seems to have started after I upgraded my software - I received an Upgrade Request when I went to iTunes and synced some stuff - could it be that?
The mic seems ok(?!) though.

Any help would be gratefully received. I've seen a few sites mentioning this problem but nobody seems to have a solution.
Thanks.

I have the same problem. My friends always say it's sounds like I'm going in and out. I thought it may have been the shape of the phone. It's kind of awkward to hold when using as a phone, I feel like the MIC is always so far from my mouth.

Mine is 4 days old & already doing this. I'm heading back to AT&T tomorrow to see what they say.