The most likely reason is that there is no telnet daemon running on the computer. Other reasons may be that you are connecting on the wrong port, or your client is on the hosts.deny list.
Under Windows the command is mstsc.Microsoft terminal server connection
what osi layers use telnet connections for remote use
You don't. Use telnet, rlogin or ssh.
Telnet allows clients to connect to other remote systems.
A single port can be configured to listen for UDP or TCP inbound connection requests (or both). Telnet uses TCP. So when you telnet to a specific IP:port, telnet will attempt to make a TCP connection. If there is no TCP listener on the port you specify, then the connection request will be refused. It matters not if you have a UDP listener on the port. Telnet will not be able to establish a connection to a UDP port.
Telnet is a Network layer protocol. It is used to create connection remotely.
ssh or telnet in company environment mostly we used ssh and there is one tool called putty, through putty we can connect.
check that the login prompt on your console has changed, and use the "show session" command
The network administor must have physical access to the device to establish a console connection whereas TELNET access can be established form a remote location. However telnet access depend upon a router with network access's, whereas a console connection can be used to access the router regardless of the router's configuration.
If you connect to the router via the console port then you are physically making a connection with a physical cable to the router. This implies you have to be close to the router itself. Using telnet allows you to connect to the router from anywhere in the network, and doesn't require a physical cable connection.
Telnet
RDP. Remote desktop protocol in Microsoft systems. Also known as terminal services on port 3389.