011-019-0274

Received calls from did numbers but the person doesn't talk when pick up the phone 011 019 0274/011 019 0288 and 011 019 0249

I have been getting calls from the 011 019 0206/ 0241/ 0274 & 0299 more and more often and every time I call these numbers the phone just rings and rings and then stops. Are these calls all spams calls

I have been getting calls Frm dis numbers and when I answer the person doesn't respond. I tried calling back but it says the number doesn't exist