@gymbody: I'm sorry to hear that you're experiencing this issue. Please can you ensure you're on the latest software by heading to Settings > Software update > Download and install, followed by Settings > Biometrics and security > Security update. Now, head to Settings > Battery and device care > Optimise now, then select Memory > Clean now. If you have a case or cover on the phone, please remove it temporarily to see if this helps. If the issue persists, please restart the phone in Safe Mode, as this will disable all third party apps and help to determine if the problem is stemming from an external source.
To enter Safe Mode, press and hold the Power button until the 'Power off' prompt appears on the screen then release > Touch and hold Power off until the 'Safe mode' prompt appears then release > To confirm, tap Safe mode.
Monitor the performance for a few hours, depending on the frequency of the issue. If you notice an improvement, restart the phone as you would normally and uninstall any recently added third party apps.
@gymbody: I'm sorry to hear that you're experiencing this issue. Please can you ensure you're on the latest software by heading to Settings > Software update > Download and install, followed by Settings > Biometrics and security > Security update. Now, head to Settings > Battery and device care > Optimise now, then select Memory > Clean now. If you have a case or cover on the phone, please remove it temporarily to see if this helps. If the issue persists, please restart the phone in Safe Mode, as this will disable all third party apps and help to determine if the problem is stemming from an external source.
To enter Safe Mode, press and hold the Power button until the 'Power off' prompt appears on the screen then release > Touch and hold Power off until the 'Safe mode' prompt appears then release > To confirm, tap Safe mode.
Monitor the performance for a few hours, depending on the frequency of the issue. If you notice an improvement, restart the phone as you would normally and uninstall any recently added third party apps.
Call reception could be your network masts @gymbody
Is this happening elsewhere or in a particular place ?
Most Network's have online network checkers.
As a process of elimination can you try your sim card in another phone and then see what happens and if possible please try another sim in your phone.
In Settings and General Management under Reset you can Reset Network Settings.
Also there is a diagnostic tool in your Samsung Members App under the GetHelp section to check out the phone too.
If all the above does not help then the phone maybe at issue and needs swapping out if still under the cooling off period if bought from Samsung directly or if not seek assistance from the source who supplied the phone.
A Samsung Service Centre can check out the phone too.
I wish you all the best. 
