Why doesn't vi(elvis) display correctly using telnet?

I am using QNX 6.2.0, and when I log in via telnet and use vi, the text is not quite correct, and changes I make don’t really show up. If I cat the file it looks fine, and if I use vi locally it looks fine. When I login via telnet TERM=ansi or xterm depending on which client I use, (Windows telnet, or putty), but neither work. I also tried setting TERM to qnx, vt100, vt102, but those all are worse. Any ideas?

I vaguely remember this being a bug in QNX 6.2.0.

I also get this behavior under 6.2.1B.
When the text has to scroll, the lines become one line offset.
Editing a line reveals it’s true content.