When it comes to MSFS, the ATC callsign is EASY (or ALPINE), flight number is 61HC. In the FMS / transponder it will be EZY61HC (or EJU61HC).
- EZY (or EJU) is the ICAO code, used for ATC and flight plan purposes (operational side).
- U2 (or EC) is the IATA code, used for ticketing and departure / arrival screens for example (commercial side).
The first code is EasyJet UK (EASY), the codes within brackets are for EasyJet Europe (ALPINE).
On the radio you would say:
- EASY / ALPINE six one hotel charlie