What Ip are you trying to connect to? Meaning is it on your own network or internet. If it's your own network Check firewalls of the computer with the ip in question. If it's on the net and not your machine, then they may have higher security in place.
If you have a router, make sure your router isn't blocking your port 23
Try this. Make sure you are connected to the internet.
before you get to your telnet, in your standard command prompt, make sure you can reach the ip you are trying to telnet. ping your.ip.add.ress
while you are in your telnet.
You should be prompted with a login, Type:
Follow the prompts if you want to complete the new account sign up or type c or close to exit it.
If you can connect to it, then your telnet is working fine.