iPhone4 - No audio during calls

I have iPhone 4 which is very nice in all the features but I have one problem with the calls. Whenever I try to make or receive any call from my phone I don’t here the audio from other end and at the other end I am also not audible. This makes it a mute call. Sometimes Instead of that I can hear some crackling noise but 99% of time I cannot hear anything from that. I tried in all Normal phone modes, speaker phone, headset plugged in but none of them helped me. This is the new one then also .showing the problem Please tell be that what can be the possible reasons behind that and how can I solve that. Any help from anyone will be appreciative.

As you told that you have bought it new so I am sure that you have the warranty card for this and it is in the warranty period. Why are you trying something by yourself? Just go to the dealer from where you bought the phone and ask them for the problem and see what he can help you. If he is not able to help you much then you can send it back directly to the Apple Service and they will fix the issue. If it has some big problem then they will replace it with the new one. This will be the best and the safest way for you to get out of this problem. If I get any problem with mine then the first thing that I do is to call the Apple support. Good Luck!!!

I was also getting the same problem earlier with my iPhone. I tried each and every possible solution that I knew to this issue but none of them were helpful for me. Finally my cousin advised me to upgrade the firmware that I am using. And by his suggestion I upgraded the firmware from 4 to 4.0.1 and that did the trick and solved the issue. Now there is no problem with the audio in call from both ends. Which firmware you have in your phone? You can also upgrade that if you have older one and this will work for you.

According to me the root problem with this is that the iPhone is not able to recognize the mode in which it is in. And therefore you are able to hear the audio during call. I think that you have to Reset your phone and that will solve the issue. It is very easy to reset the iPhone, just follow the simple instruction. Switch the phone off and hold the press and hold down the sleep and home buttons. Now start your phone by holding those keys. You will be able to see the Apple logo on the screen. When this logo appears then you have to release the buttons and this will start to reset the phone and do all the other things automatically.

OK, you can reset your phone and see whether it helps you or not it that does not help you then you have to restore your phone and to do that you have to click on the restore button that you can find under the summary tab. If you restore you phone then this will erase all the contacts from your phone and also the calendars, photos and other data. But it will back up the information like text messages, notes, call history, contact favorites, sound settings, widget settings, etc. But remember that you make this as the last option if nothing helps you. I hope that this will able to solve the issue for you. You should take the back up for all the contacts from the phone because it will be going to be deleted.

If you have updated to 4.0.1 and you have not jailbrocken the phone Then you can try the following to get it fixed. Go to Settings > General > Reset > Reset All Settings and this will reset your phone to a new iphone settings and you will not have to use the backups.I hope that this will help you to solve the issue.