Suspending emacs on character terminals and "screen switching"

[Casper Gripenberg]

Does anyone know what the terminal capability is that
makes emacs switch back to the "shell screen" when you
suspend emacs?

I made a gif animation showing what I mean:
http://zoidberg.homeip.net/schtuff/EmacsSuspendSwitch.gif

I run emacs on two computers. One is OpenBSD and the
other FreeBSD. Emacs works fine on both but on FreeBSD
I can't get it to "switch screens" when I suspend it.
No matter what terminal type I set.

The screen switching is really useful when having to
suspend emacs and go back to the command line to see
what your program output was, or part of a manpage or
whatever.

Why can't I get it to work on FreeBSD? What terminal
capability or setting is missing over there? I'm sure
I could tweak a termcap file or something and get it
going, but I can't figure out what it is emacs is
looking for to activate this switching feature.

Look in the video. Setting term to xterm activates
the behaviour, setting it to vt100 disables it.

Anyone got any ideas how to get emacs to do this
on my FreeBSD box too?

Casper