Network Firewall Requirements
GoSpotCheck is hosted in Amazon Web Services, which uses dynamic IPs for things such as load balancers and servers that change as new versions of the application are continuously deployed.
The mobile applications use these same requirements, but also communicate with additional services, such as Google Maps API, Urban Airship (for push notifications), and Amazon's S3 service.
All communication inbound and outbound to the mobile applications is done over standard HTTPS on port 443, so if you are not requiring hostname whitelisting for the networks that the mobile applications will be running on, then having outbound port 443 should be sufficient.