I'm not sure you understand what I posted. The gate agent = (normally airline but might be an airport contract worker at outstations) employee responsible for boarding the aircraft at the gate, and positioned just before one enters the jetway or steps outside to board an airport bus to the aircraft at some remote stand is ultimately responsible. You would have contact with this person after you've dealt with the check in agent. In other words, calling in advance or getting past the check in agent at the airport on the day of departure doesn't necessarily mean that you will get permission to board the flight.