I get these calls all the time on my cell phone ( only family has my cell number)  i always check here after declining to answer the call to see who these people are that are calling my cell phone.  Obviously they are unknown to me as only their number appears on the caller info and no name associated as being a contact stored in my phone
I simply BLOCK these morons then they call from some other number and I BLOCK that number also
out of hundreds of calls I have yet to get any of these unrecognized numbers that have been important