It's a common issue with the oddball SMRS (short message relay system?) that Delta uses. Gate assignments are stored in this lovely thing called a 'SMRS table", which equates gate GGG in city CCC with computers KKKKK1, KKKKK2, KKKKK3, KKKKK4, hardcopy printer PPPPPP, and so on and so forth.

Long and short of it all, it's a complex system so that the gate receives a one line printout when the flight is in range and then so that ACARS can be sent at flight closeout. I never quite got why the gate mattered in all this, as ACARS is obviously not gate dependent, but it was a pest when you had a last minute gate change in an outstation where the gate assignment couldn't be changed and you could only send numbers from a computer at the "SMRS" gate.