Collusion in online poker is relatively easy and much more difficult to immediately spot if executed well. Cheaters can engage in telephone calls or instant messaging, discussing their cards, since nobody can see them. Sometimes one person may be using two or more computers to play multiple hands at the same table under different aliases (since many broadband plans offer customers multiple IP addresses, this can conveniently and cheaply be done without the likelihood of immediate detection). Such tactics can give cheaters an advantage that is difficult to work against. Online poker cardrooms keep records of every hand played, and collusion can often be detected by finding any of several detectable patterns (such as folding good hands to a small bet, as it is known that another player has a better hand). Users who frequently sit at the same tables will be flagged by poker rooms and their play will be closely monitored. Often, such users will be warned they have been flagged, in an effort to deter collusion.
