Win7 inside Use the telnet command why you are prompted that Telnet is not an internal or external command, or a program or batch file that can be run

Win7 default does not install Telnet function, so you directly with telnet command is not used;
You can go to "control Panel"-"program" (in the bottom left corner)---"Turn Windows features on or off", check "Telnet client", OK to use the Telnet command normally.

If you can't find it in a simpler way, click on the right mouse button, the properties

Then search for keywords

Win7 inside Use the telnet command why you are prompted that Telnet is not an internal or external command, or a program or batch file that can be run