Have you tried Juice SSH as a Telnet client for Android? The basic package is free & works quite well for me so far. (Very good ANSI display & it lets you use whatever keyboard you prefer.)
So far, I use it exclusively for playing BBS Door games via a Telnet connection.
(Usually using port 23; Incidentally, why does IPX networking fail for ports below 1024?)
Personally, I would like to run a BBS via Telnet from my phone. I find plenty of “Telnet” server apps, but none that will let me run legacy code for Door games & such features. I am hoping to install Win95/98 & run a BBS or possibly just TWGS, inside Magic DosBox.