Hi,
Check in the Dialing app settings that outgoing calls have not been barred.
Not sure if it is applicable to Samsung, it is on my Android phone, but try the following:
Go to Phone app > more > Settings > call blocking and see if there is an option to block outgoing calls.
(on my phone it is Phone app > Settings > Voice call > call barring > All outgoing calls > enabled/disabled.)
Hopefully this is of some help.