Checking in for your Frontier Airlines flight is simple with their online and mobile check-in options. This allows you to choose your seats in advance and receive your boarding pass electronically. Be sure to check in 24 hours before your scheduled departure for the best seat selection. If you have questions or need assistance related to Frontier Check In, you can visit the Airlines Pet Policy. Additionally, you can contact at 801-401-9000 or +1-844-902-4930 (OTA Skip-Waiting).