Hi,
Indeed you could use AirlineFlightSchedules or just Scheduled(for next 24 hours https://flightxml.flightaware.com/soap/FlightXML2/doc#op_Scheduled )
From your message I understand that you would like the returned AirlineFlightScheduleStruct to have the flight number, right?
Looking at the returned AirlineFlightScheduleStruct I see there is an actual_ident(meant to give you the operating carrier) and an ident field (for the marketing airline):
https://flightxml.flightaware.com/soap/FlightXML2/doc#type_AirlineFlightScheduleStruct
I may misunderstand your question, but you could find the flight number from one of these 2 idents.
So for example here I request next 3 schedules between Charles de Gaulle Airport and Schiphol Airport:
https://flightxml.flightaware.com/json/FlightXML2/AirlineFlightSchedules?startDate=1455206406&endDate=1455306406&origin=LFPG&destination=EHAM&howMany=3
and I get:
{"AirlineFlightSchedulesResult":{"next_offset":3,"data":{"ident":"KQA3034","actual_ident":"AFR1440","departuretime":1455209400,"arrivaltime":1455213900,"origin":"LFPG","destination":"EHAM","aircrafttype":"A321","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0},{"ident":"KLM2022","actual_ident":"AFR1440","departuretime":1455209400,"arrivaltime":1455213900,"origin":"LFPG","destination":"EHAM","aircrafttype":"A321","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0},{"ident":"AMX6508","actual_ident":"KLM1244","departuretime":1455212400,"arrivaltime":1455217200,"origin":"LFPG","destination":"EHAM","aircrafttype":"B738","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0}]}}
Origin and dest are optional, so if you want schedules by operating carrier for example Air France you could use something like this:
https://flightxml.flightaware.com/json/FlightXML2/AirlineFlightSchedules?startDate=1455206406&endDate=1455306406&airline=AFR&howMany=3
with result:
{"AirlineFlightSchedulesResult":{"next_offset":3,"data":{"ident":"AFR7980","actual_ident":"BTI349","departuretime":1455225300,"arrivaltime":1455227940,"origin":"EVRA","destination":"EYVI","aircrafttype":"B735","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0},{"ident":"AFR4835","actual_ident":"AEA6072","departuretime":1455205500,"arrivaltime":1455208500,"origin":"LEPA","destination":"LEBL","aircrafttype":"E190","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0},{"ident":"AFR3597","actual_ident":"DAL476","departuretime":1455237000,"arrivaltime":1455264900,"origin":"KJFK","destination":"LEBL","aircrafttype":"B764","meal_service":"","seats_cabin_first":0,"seats_cabin_business":0,"seats_cabin_coach":0}]}}
Does this help?