Can’t hear call sound unless on speaker is on

Hello sasmita34,

Thank you for reaching out in Apple Support Communities. There are steps we recommend for you to follow that may help to resolve the ability to hear callers through the receiver of your iPhone. Here are the steps:

1. Remove all screen protectors, films, or cases from your device. 

2. Check the speaker opening to see if it's blocked or dirty. On iPhone only, make sure that the receiver isn't blocked or dirty. 

3. If necessary, clean the speaker or receiver opening with a small, soft-bristled brush. Make sure that the brush is clean and dry.

4. Go to Settings > Sounds (or Settings > Sounds & Haptics), and drag the Ringer and Alerts slider back and forth a few times. If you don't hear any sound, or if your speaker button on the Ringer and Alerts slider is dimmed, your speaker might need service.

5. If you hear sound, try making a call with your iPhone and turn on speakerphone. On iPad or iPod touch, make a FaceTime call. If you still can't hear, or hear static or crackling, then your network or reception could be the issue. Try to call again later, or from a different location.

This may help resolve your issue and is outlined in this helpful article: If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker

Best regards.