上面两个回答都不对。
ban:屏蔽、拉黑、禁
屏蔽:if someone 屏蔽了你, it means that he can't receive your message anymore. This word is usually used for radio signal or wireless signal. For example, mobile phone, WIFI etc.
an example: 我不能再用小王家的WIFI上网了,我怀疑他把我屏蔽了。
拉黑:拉入黑名单。If people don't want to receive any message from someone, he can 把他拉入黑名单。Normally a mobile phone has this function, meaning that you can 把someone 拉入黑名单。We say:把×××拉黑。For example, 这个号码是骗子的,我已经把他拉黑了。
Some web site can 拉黑 its client too. For example, I am an admin of some web site, I found 25.169.240.6 is a hacker ip, so 我把他拉黑, then he can't log in my web site anymore.
禁:this word is usually used on the Internet. For example, rgc is a game platform. I am a player who uses some illegal software to cheat in the game. Now the admin find that I am a cheater, so he 把我禁了. Now I can say: 我被××游戏平台禁了。
Or if I speak a lot dirty words, I may be 禁言. 禁言 means 禁止发言. I can still log in but I can't talk.
Basically, 屏蔽 = 拉黑. Both of them can be used about mobile phone or Internet.
禁 is normally just used on the Internet.
BTW, sometimes, you can even say: 我被ban了 ----- as long as people know english.