You do speak to a call center, even if you are in the resort.
For say, a request like a pak n' play, the CM at the call center/reservations notes it on your reservation. When you check-in and your room is released for occupancy, it will be noted on the computer by Mousekeeping and they will place it in your room.
Any other requests, I.e. close to bus stop, will be noted by the room assigner when reservations rolls over the reservations via computer to the actual resort.
The only time an actual call will go to the front desk is if the CM feels it warrants being transferred. Disney assigned a different number to each resort, so the person at the call center could answer as if they were actually in the resort. It is all about the illusion that you are talking to someone at the front desk, but it allows the front desk to concentrate on those actually at the resort.