Exactly londo, the individual publishers make records of anyone who they deem needs to be called back on including the deaf, and householders who speak a language other than their own. They pass these slips on and the elders arrange for someone to follow up.
I remember calling on a person whose mother sent a letter to the cong requesting someone call even though the person wasn't the slightest bit interested.
They may not have an official database technically speaking, but they certainly have records and info on individuals.