I only use a cell phone, they call me constantly. This is the first time for this number. If I don't know the number I don't answer. I figure if it is important they will leave a message. I am on the DNC list which is a waste of time and space ... think about it ... it is a government run agency.
Probably a good idea to just not answer unless you recognize the number. The last time I changed my number the cellphone company charged me $25.00 to change the number.