the port numbers are just down the which port the server owner runs the software on on their server, it's unlikely that you will get two lines using the same port but not impossible, it could be they are using the default port that their software has set and not changed it to something else.
if your line and the one you purchased for your friend are from same provider then everything will be exactly the same apart from username and password.
Don't worry about port numbers, they can be 4 or 5 digits long