How do you know the ip who talk to you in the facbook?

How do you know the ip who talk to you in the facbook?
1) Open start, select run and type "CMD".
2) Begin talking to your friend.

3) Open CMD and type "NETSTAT".

4) It should then come up with an IP address/addresses if you are talking to more than one person.

Note: This may not work if the website has a proxy server which could block it.