@Ivana81: To troubleshoot the issue please open your Phone app > Tap the 3 dots in the top right corner > Settings > More Settings > Call Barring > Voice Call > All Incoming Calls > Ensure this option is switched off.I also suggest that you restart the phone if you have not done so already to address any temporary software issues that may have arisen following the update. A lot of users complain that they cannot make outgoing calls on Samsung and other Android phones. I have done the contact us on the phone where you upload a system log as soon as the fault occurs but so far I have had nothing back from Samsung regarding this issue.
2 nd Method: Check network signal strength to fix call dropping problem on galaxy S9 and galaxy S9 plus.

To fix poor sound call quality on Samsung galaxy S9 plus, find nearby place that good network signal. A lot of users stated that the audio level of their Samsung Galaxy S9 or Galaxy S9 Plus is not sufficient for their usage. Samsung MMS Problems; Samsung Not Recieving Calls; How to Fix Can't Answer Incoming Calls on Samsung S9/S10 Issue “Recently, I have faced with a weird issue. Samsung has been promising a software update to fix the problem. If network signal strength is bad in your galaxy S9 & S9 plus, you can’t hear call for incoming or outgoing call. How To Fix When Samsung Galaxy S9 Or Galaxy S9+ Can’t Hear Calls Switch off your Samsung Galaxy S9. There might be debris, dirt, or dust stuck in your microphone.

There can be multiple reasons for this problem from occurring. The Galaxy S9 and Galaxy S9+ received an update with the April 2018 security patch late last month, but a separate update is now rolling out with call stability improvements. The Samsung Galaxy S9 and S9 Plus are both affected by an extremely annoying problem with the Microphone, which prevents the most basic function of making and receiving calls and using other applications that require the phone’s microphone. Press and hold the Power key past the model name screen appearing on the screen.

When the failure occurs, only the other party can hear the sound, which means that there is a problem with the handset of the S9, which is sometimes as long as 20 seconds. A weak signal can stop a user from doing even the basic thing like making calls from the device. This … However, we fail to understand, how a hardware-related issue (if this is one) can be fixed through software updates. The problem seems to be in several Android devices, and not related to a specific brand. Note that audio issues corporates voice-related problems especially when you’re using your Samsung Galaxy S9 or Galaxy S9 Plus for phone calls.