IRC4Fun offers hostmask/IP cloaking to both un-registered Guests as well as registered (and identified) users. Guests are partially hidden or cloaked. Registered users are given a full cloak (vhost).
If you are trying to connect to IRC4Fun, but are being told you are either A-Lined, K-Lined, G-Lined, GA-Lined, or Z-Lined; this guide explains why and how to go about appealing the ban.
There may be cases where your Nickname is either in use or held by Services -- either of which can be resolved. (If you have registered your nickname with NickServ.)