We spent some time training Juniper that behind doors lies Squirty Monsters, and now he just sits there even if the door is open. We get to do it again when Cat #2 shows up in a few weeks.
Neither will wear collars or be chipped, at least for the foreseeable future. We do worry about them getting out, but for us it's more an issue of our neighborhood. There's dogs on both sides, and then dogs again past that. Behind is an alley, in front is a 1-way street. There's a feral colony up the street of about 10+ cats, fed by a group of families, and a few stray cats that wander through the yard on occasion (since, as mentioned, there's dogs on both sides). If Juniper were to get out, he would hopefully
hide under the porch or deck, or rush back inside if we were there. If he got beyond that, we'd have more luck with posters than collars, simply because there's no way we'd get Juniper to wear a collar (and if we got him a breakaway one, which would be preferred, we'd wake up every morning to a collarless kitty
), and no one around here knows anything about checking microchips.
I wouldn't mind getting him a collar if he was more interested in the outdoors, but we've been focusing on training him and he's been excellent at learning that outside = bad.