Hey Bonny777,
Were you able to go through the steps in the article and also make sure the device is up-to-date. The article addresses the issue you're experiencing with the iPhone becoming unresponsive during a call. Updating the iPhone ensures all security updates and fixes are installed.
Since you're only experiencing this issue when you're on a call, make sure you're getting a good signal during the call. The issue could be network related. Also, make sure that the carrier settings are up-to-date.
"Carrier settings updates let your carrier provider update carrier network and related settings to improve cellular network connectivity and performance." To check for updates, follow those the steps below or in this article: Manually update your carrier settings on your iPhone or iPad.
- "Make sure that your device is connected to Wi-Fi or a cellular network.
- Tap Settings > General > About.
- Follow the onscreen instructions to install your carrier update.
If you set up a new eSIM or insert a new SIM card into your iPhone or iPad, you might need to download the carrier settings for your new carrier."
In regards to the volume during a call, are you lowering the volume by using the volume buttons or are you going into Settings > Sounds (or Sounds & Haptics)> Ringtone and Alert Volume? If "Change with Buttons" is disabled, enable it, and try lowering the volume during your next call.
Also, test using the speakerphone and headphones if available. This will help further isolate the volume issue.
Hope this helps. Take care.