Apple has a bit of an easier time, because they can (and do) lean on cellular carriers that restrict access to their push servers. And they have 17.0.0.0/8
But they say port 5223 and 2197 with fallback to 443 [1]. Google says 5228-5230 and 443, with a couple outliers [2].
But they say port 5223 and 2197 with fallback to 443 [1]. Google says 5228-5230 and 443, with a couple outliers [2].
[1] https://support.apple.com/en-us/102266
[2] https://support.google.com/work/android/answer/10513641?hl=e...