Q: I Try calling on my IPhone 4 And the person on the other side can not hear me how can i fix that?

Hello there, Colleen1345.

The following Knowledge Base article offers up some great steps for troubleshooting the very issue you're describing:

iPhone: Microphone issues

http://support.apple.com/kb/ts5183

Follow these steps, testing after each.

1. Make sure nothing is plugged in to the jack connector.
2. Make sure nothing is blocking any of the microphones (refer to the pictures below to find your device's microphones). Check for these:
   • Dirt or debris
   • A screen protector or case
   • When you're holding your phone next to your ear, make sure you don't block the microphone with your fingers or shoulder and make sure to speak into the microphone
3. Turn the iPhone off and then on.
4. Update to the latest version of iOS.
5. If necessary, find general iPhone hardware troubleshooting suggestions.
6. For further assistance, contact Apple Support.

If the issue persists and you need to make a call, try using headphones with an integrated microphone.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro.