[fragmede]

Not really. Apple gives T-Mobile the hostnames/IP addresses they use for iMessage, and T-Mobile configures their APN to only allow connections to those addresses. There's a lot that happens on the backend for cell data to work that consumers don't see.

[jahlove]

They need to know more about the payload, so that they don't try to upload a video through starling, for instance.

[vineyardmike]

Already solved on in-flight wifi.