Crew Scheduling actually has 3 different phone systems. The standard system is dialed through the computer. When they pull up a rotation and assign it to you they click on your name it it dials your number. It is a all digital computerized system and is not compatible with caller ID. It will come up Unknown Caller on your caller ID. Anytime you see Unknown Caller consider it about the same as "Danger Will Robinson, Danger"
The automated system they use when they get behind and need people now is a blast calling system. I believe it does show a caller ID.
Phone calls from supervisors ect.. will usually show up as Delta Air Lines if direct dialed. That is why sometimes you get a caller ID and other times you don't.