Emergency Call Up's are free agents that you add to your roster for one match day because you have at least two players on your four man roster that will not show up. You can give the free agent an ECU, and they are your player for the night only. Here are the other stipulations.
1) You cannot make an ECU until a match day, but you can inform the player that you intend to do it so they can be ready.
2) If you make an ECU, you must deactivate a
the players required to qualify for an ECU in his/her place. That assures that the player being picked up is TRULY an EMERGENCY call up.
3) You can make the ECU for only certain games of the match day, but you must specify which ones. Example: You can sign Player A on an ECU for games 1-3 and deactivate Player's B and C for games 1-3 of a match day. Player A would become a FA again for game 4 and Players B and C would be allowed to play game 4.
4) Because deactivating 2 players is required for the ECU, if you activate just one of the deactivated players, you would have 3 players on your team that can play, so the ECU would become a FA again.
5) A GM must provide a valid reason for his players not being able to show up. If it is proven that they were able to play, that team is liable for a points sanction. ECU's are ONLY for when your players CANNOT SHOW UP.