Call blocker might be of some help. Also don't pick up on numbers you do not recognize, or where there are caller IDs that seem odd. Or where there is no caller ID.
Keep getting calls from 313 numbers that I don't know, I think telemarketers are getting smarter and calling you from your local area code in hopes you'll pick up...I have learned my lesson to not even answer local area codes if I don't know who it is.