SMS don’t work

Hi,

I’ve got from my son an iPad Pro. I need to be able to recieve sms becuase some apps require it for autentification purposes. I’m able to send imessages but doesn’t let me send or recieve an sms. I have a sim card. When I put my iPad sim card to my phone than it can recive and send sms but it doesn’t work in the iPad. I tried to restart the iPad nothing happened. I didn’t find any settings where I can allow sms (text message) to work. I could only find an option to turn on or off the imessage. I hope someone can help me. Thank you in advance! Istvánné