Whenever we contacted or were contacted by a new owner of a home with one of our alarms in it, I would offer a free visit to teach the use of the alarm. The first thing I always did was ask what codes they want to use, replace the old ones and disable monitoring. Then I would teach the use of the system, sell a new battery if needed and offer monitoring service. If they went with the service the battery was free. Either way, no charge for the visit. That way I could always be certain that both of our receiver numbers were out of the panel in case they went with another company later. Far too many times we'd find that some moron "tech" would go out and program only the first receiver number, leaving our backup number active.