Phone Banking is the act of cold calling people and asking them to take action. This sort of action comes in many different forms. For example, you might be asking someone to pledge to vote for so-and-so candidate or such-and-such proposition. Or, you may request that the receiving party leaves a voicemail with their state representative.
I grew up in a small Catholic town in Massachusetts called West Bridgewater. It was a town so out of the way that even the