Samsung
Turn Call Barring On or Off auf Samsung
Call barring is a network-based restriction, not a phone-side block list. It runs through your carrier and can silently reject specific call types, such as all incoming calls while roaming or every outgoing call once enabled.
On a Samsung phone, this option lives under Phone ➔ Menu ➔ Settings ➔ Supplementary services ➔ Call barring. From there, choose either Voice calls or Video calls, since the two are managed independently and one can be barred while the other still works.
Inside each category you get separate toggles, for example for outgoing calls, incoming calls, or incoming calls while roaming. Turning any of them On or Off requires a network password issued by your carrier, not your device screen lock or Samsung account password.
If calls are dropping only in specific apps or with specific contacts, Call barring is not the cause. Check Do not disturb settings or a contact-specific block list instead, since those work independently of the carrier and do not need a network password.
Disabling Call barring by mistake can leave your line unprotected against unwanted charges while roaming. Only change it after confirming the correct call type and direction, since the wrong toggle can cut off calls you actually want to receive.