I recently picked up a change of address packet from the Post Office. Inside was an ad for OneSwitch, a service that claims it will "processes a change of address for all subscriptions with a single call so that they will continue without interruption after a move." This service is free to the caller, so I wondered how it paid for itself.
I found the answer here. " OneSwitch provides businesses with the opportunity to capitalize on the New Mover market - the most prolific buying audience in the country - when callers are on the line to complete their change of address." SDP, who runs service, tries to sell you stuff while you are on the calling them to switch your subscription addresses. Plus they can build a database of movers which they can sell to other companies.