Is your phone Do Not Disturb mode is TURNED ON
Please check if your phone's do not disturb mode is turn on. If so, please help to TURN it OFF
For iphone : https://support.apple.com/en-us/HT204321
Is the caller's number blocked ?
Please help to check if the caller's number is blocked by your mobile phone. If so, please remove it.
For iPhone : https://support.apple.com/en-us/HT201229