/sys$common/syshlp/helplib.hlb TELNET, Qualifiers, /PORT  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /PORT=n

    Optional. Default: 23.

    Remote port to which you want your TELNET process to connect.
    Specify only if you are connecting to a host that does not use
    the standard TELNET port.