Hello Mohamed . I’m Nehal , Samsung Moderator.
Thank you for asking the question
Based on your writing If in trouble you face in the network
In regards to your query, kindly follow the below steps:
Make sure that the device does not encountered any issue like dropped in any liquid or fall on solid floor
Change the network mode and see if that will make any difference through
settings – connections – networks – mobile network settings – network mode
Check if calls can be made after switching the phone off and on.
check the device with another SIM card
try the sim card in different Mobile phone to check whether the issue with the phone or the Sim card
if another SIM card works with the device kindly contact with the network provider in order to fully assist you
if the issue still exist we recommend that you perform a factory data reset to resolve this issue using the steps below:-
Launch the Settings app and tap General management → Reset → Factory data reset →
RESET → DELETE ALL.
Ensure all user data is backed up using smart switch
from the link below and then use the backup tool to create a data backup
If you’re still facing the same issue, kindly take the device to the service center to check on it.
As for the Galaxy A50 update (ready for launch in April 2020)