Patent ID: 8433752

Claim:
A method, comprising: causing a user terminal corresponding to a first user to join a chat session including at least one other user and initiated by one of the at least other users, the user terminal comprising an instant messaging client, wherein the causing comprises sending by the user terminal a session initiation protocol subscribe message to join the chat session and receiving at the user terminal a session initiation protocol message indicating the user terminal has been joined to the chat session; receiving, at the user terminal and subsequent to the user terminal joining the chat session, a session initiation protocol notify message that identifies a second user, wherein the second user is another one of the at least one users which has joined the chat session or is already in the chat session as another one of the at least one other users at the time the first user joins the chat session; checking, at the user terminal, with the instant messaging client whether the second user is listed in a blocklist of users blocked from communicating with the first user, wherein the blocklist contains a list of users blocked by the first user; and in response to the second user being listed in the blocklist, notifying the first user via a user interface of the user terminal that the second user is listed in the blocklist.