I was researching the issue you are describing and found an article that just may get you going. It is called iPhone: Can't hear through the receiver or speakers found here: http://support.apple.com/kb/TS1630.
When someone calls, I can't hear them through the receiver or speaker phone, and I can't hear music through the speaker. I also can't be heard by someone who is calling me.
Note: iPhone has one speaker, which is adjacent to the dock connector. On iPhone 4 or later models, the speaker is to the right of the dock connector. On earlier iPhone models, the speaker is to the left of the dock connector.
- Verify that there is nothing plugged in to the headset jack, including headsets, headphones, or adapters.
- Make sure the Ring/Silent switch is not switched to silent.
- While on the Home screen, adjust the volume buttons. If you see the icon below, indicating that headphones are attached, there may be debris or an object lodged in the headset jack:
- Check the headset jack. If there is an object lodged in the headset jack that is not easily removed, have the iPhone serviced to remove object.
- For Original iPhone: If there is light debris, such as lint, in the headset jack, try connecting a pair of headphones to the headset jack and then remove the headphones. Repeat this several times to remove the debris.
- If you have installed a protective film on the display, either ensure that the receiver is not covered or remove the film completely.
- Check the receiver mesh (which is on the top front of the device, above the display). If it appears blocked, use a clean, small, dry, soft-bristled brush to carefully and gently brush away any debris.
- If you have paired with a Bluetooth headset that is nearby, either use the headset or turn Bluetooth off (chooseSettings > General > Bluetooth).
- Restart the iPhone.
- If restarting the iPhone doesn't resolve the issue, try restoring the device.
- If the issue persists, go to the Service Answer Center - iPhone for information on service.
For other troubleshooting tips, see:
- iPhone: Sound muffled or low from the speaker or when speaking into the mic
- iPhone: Hardware troubleshooting
All the best,
I had the same issues and none of cleaning headset jack with cotton swab, cleaning debris and restarting the iPhone worked. It seemed like It happened after I updated a software so I did the following as suggested by apple support and it worked.
Use iTunes to restore your iOS device to factory settings
You can use iTunes to restore your iPhone, iPad, or iPod touch to factory settings and the latest version of iOS.
Restoring iOS software deletes all your data and content from your device, including songs, videos, contacts, photos, and calendar info.
Before you restore your device
- Make sure you’re using the latest version of iTunes.
- Use iTunes to back up your device. Transfer and sync any additional content to your computer.
- Turn off Find My iPhone in Settings > iCloud on your device to disable Activation Lock.
Restore your iOS device
- Connect your iOS device to your computer using the cable that came with it.
- Select your iPhone, iPad, or iPod touch when it appears in iTunes. In the Summary panel, click Restore.
- Click Restore again to confirm that you want to restore your device to factory settings and delete all data and content. iTunes will download the iOS software file and restore your iOS device.
- After your iOS device is restored to factory settings, it will restart. Once it does, you’ll see the "Slide to set up” welcome screen. Follow the steps in the iOS Setup Assistant. You can set up your device as new or using a previous backup. If your iOS device has cellular service, it will activate after you restore.