I haven't heard of an "Astron 3000/16" either, and there are no pics attached to your post. Pictures of your Control Panel, as well as keypad,might be helpful.
In Alarm-speak, "Control Panel" (CP) refers to the actual "brain" of the system---the keypad is usually just the interface between the CP and the User (you), but a picture of it is often helpful. The CP is usually located in a steel cabinet somewhere, usually about the size of a small bathroom medicine cabinet.
Sometimes an chain of dealerships (like ADT or Protection One) will re-brand (re-name) a popular alarm brand model, for vendor lock-in reasons (they want their customers dependent on them, not on competitors). For instance, ADT's "Safewatch Pro 3000" Panel is actually a Honeywell Vista-20P Panel. If Astron is one of those dealer chains, it might be using a DSC PC3000 panel, Napco MA3000 panel, or one of the earlier Ademco/Honeywell or other now-defunct brands. The actual model number, from the actual manufacturer, might not even resemble the Dealer name for the system. That's why pictures of both the CP board and keypad can be important to identify the CP we're working with.
AGAIN: What part of the world you're in might be relevant: North America, Brazil, Portugal, Galacia, UK, Korea, or where?
