Samsung s9 only calling, texting on wifi

[Ephyd]

Just bought a Samsung s9 off a friend. When you put a simcard and call it say "not registered on network." But the moment you just connect to WiFi it works fine. Receiving and making calls. Even network configuration sms received. Wat could be the problem. Is it blocked or the phone has issues?

[AndrewL]

@Ephyd: Do you have Wi-Fi calling enabled on your mobile contract? If possible, are you able to try your SIM card in another compatible device to see if the issue persists?

[Ephyd]

The Sim works in another device.

[Ephyd]

I don't know if wifi enebled. But the moment I turn of wifi the phone stops working. No incoming or outgoing calls