This message is written to the syslog during diagnostic processing. Basically the terminal type specified during telnet negotiation was unsupported. Processing will continue but it will act as a dumb terminal. This means that all full screen applications will not work. Character-at-a-time raw mode applications such as vi will not work with a dumb terminal because they require full screen cursor support. Terminal types identified as 3270 will be changed to DUMB terminals.