I tried to build an apartment from scratch. No shell. And I got everything working fine.
But when my Sim clicked on the callbox there are dozens of Sims listed on it. Well I'm not sure of the exact number but It's got to be over twenty.
There are four NPC doors in the building. On the same floor as my Sim.
When she rings the bell, one person comes out from each door. But when she uses the callbox and calls them out, they appear out of the elevator and into the lobby and as I said there's a lot of them.
I'm not sure if it's something I've done or didn't do that caused this to happen.
I've looked around and I've read about people having trouble with NPC's not moving in, but not with people having problems with too many Sims.
Does anyone have any ideas of why this happened or how to fix it?

I haven't made any apartments from ground myself in sims3, but I think that's a new one. To me it sounds like a bug. There's usually more people in the discussion sims3 forum, perhaps someone there know?

I've experienced this, too. I built a Bed&Breakfast place that had one room apartments in it, and there were around 20 sims crammed into a tiny room! From what I've read around the various forums, this seems to be by design (perhaps to simulate 'roomies' in a rented apartment). I've not had them all come out of the room when using the call box though, usually only one at a time is called.

I'm curious. What world did you get this issue in?
I built in Sunset Valley when this happened. I then tried to build one in Bridgeport and the opposite happened. No body moved in. I heard that some times in Bridgeport it takes longer to get tenants.
I wonder if it has anything to do with the way things are set up in the different Worlds.. Like maybe it's too easy to get tenants in Sunset Valley. Maybe they, EA were expecting people to keep apartments to the city? Dunno Just guessing. If you say you built your building that was overpopulated in Bridgeport then my theory is blown.

Nope, it's a custom world that I'm currently building, it's just a suburb and not a city.

I've experienced something similar, i have built a couple apartments from scratch in Twinbrook and they're usually packed with sims, not dozens though, about 6 or 7.
I've asked about this to Twallan( mod maker), it seems that otherwise homeless sims in town go to the apartments, so if you've built in Bridgeport, which full with apartments, there won't be many sims left to occupy those.
I think this is an EA design, but it could be Twallan's Story Progression mod i use.

I would there is some kinda limit to the amount of sims fitted in a npc apartment.
Just today i've built a big apartment building but with only two npc doors, by the moment i went with my sim to check on it, it was already full with residents.

From what I've seen, it depends on whether you've got any other apartments in your world before you start playing. If your world has no apartments at all and you build one - and only one- and then go back to gameplay, then every single possible homeless/NPC etc that the game can find will be crammed into that building. If you place several apartments before going back to gameplay, then the potential tenants get distributed more or less evenly. Ish.

Bridgeport already has a ton of apartment style buildings, so when you build a new one the game has to wait for the next available homeless to stuff in there. Whereas in Sunset Valley, there are no apartments to compete with and you end up with insane numbers hiding behind however few NPC doors you gave it.

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The only mod i had in when I made this apartment was the one that allows you to see the mailbox..Otherwise no mods or CC. What you're saying makes sense though.


Yeah that seems like it would be why it's actually hard to get residents in new Bridgeport apartments.
I'm going to place a few clones of my apartment in Sunset Valley just to see if the number of tenants drops when there are several apartments available.