Open a network login connection to host named HOST (a string).
Optional arg PORT specifies alternative port to connect to.
Interactively, use C-u prefix to be prompted for port number.
Communication with HOST is recorded in a buffer `*PROGRAM-HOST*'
where PROGRAM is the telnet program being used. This program
is controlled by the contents of the global variable `telnet-host-properties',
falling back on the value of the global variable `telnet-program'.
Normally input is edited in Emacs and sent a line at a time.
(fn HOST &optional PORT)