annoying Indian voice caller

This call and calls from this number 023997568 have been calling me all day today. No one speaks and you can not return the call

Calls several times a day, no one on the other end. Call the number back to get an answering machine telling me that the number is incorrect or cant be connected..

Scam, said his name was John Wilson, calling from Telstra, I have nothing to do with Telstra