tset is being run. Something is not ok with tset. You need to fix that From man 1 tset 
Tset  initializes  terminals.   Tset  first determines the
type of terminal that you are using.   This  determination
is done as follows, using the first terminal type found.
       1. The terminal argument specified on the command line.

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And further down 
Once the terminal type has been determined,
the terminfo entry for the terminal is retrieved.   If  no
terminfo entry is found for the type, the user is prompted
for another terminal type.

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This stuff is gold I tell you GOLD 
TERMINAL TYPE MAPPING
When the terminal is not hardwired into the system (or the
current system information is incorrect) the terminal type
derived  from the /etc/ttys file or the TERM environmental
variable is often something generic like network,  dialup,
or  unknown.   When tset is used in a startup script it is
often desirable to provide information about the  type  of
terminal used on such ports.

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And further down still 
/usr/share/terminfo
            terminal capability database

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In reply to Re: Net::Telnet "unknown terminal type" by blm
in thread Net::Telnet "unknown terminal type" by jlee

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