Hello Dbalchin,
We understand that you're having issues specifically with the call volume on your iPhone.
Firstly, we suggest you start with the steps in this guide.
If that doesn't help, is the issue consistent when using the receiver, speakerphone or a headphones?
Be sure to:
- Remove any cases or covers from the iPhone and test the call volume.
- Check the Ring/Silent switch and make sure it's set to "Ring".
Next, follow these steps and see what your results are:
- Go to Settings > Accessibility > Audio/Visual. From here, slide the audio slider all the way to the right.
- Open Settings > Sound & Haptics > Ringtone.
- Tap any ringtone to play it.
- Repeat steps 1-3, this time move the slider all the way to the left.
If you hear no sounds or muffled sounds, from either or both speakers, you may need service: iPhone Repair and Service
If the sound is normal, then try to make a FaceTime call to see if the audio issues persists there.
- If the audio is normal, and only cellular calls are affected, then this is an issue on the carrier's side.
- If the audio issues continue in FaceTime, then hardware service is likely needed.
We hope that helps you out!