So about that! There's this iOS app called Flightly that does a brilliant little hack where the app updates itself in (almost) real time on the "free messaging" plan. The way it works (according to a friend) is that their servers send your phone a push notification every couple of minutes from take-off until landing, containing some serialized info such as lat,long,alt,eta,etc. And then the app immediately swallows the notification and deserializes its content without you ever seeing it. The notification works because in order for Alaska to give you notifications at all for your messaging apps, it needs to give you access to _all_ push notifications as they all get sent over an encrypted connected through Apple's server and it can't pick and choose which apps' notifications it lets through.
I've often wondered if it'd be possible to pipe any sort of internet over notifications but I'm not sure if e.g. inline responses are viable, and also that'd probably be heavy enough usage of push notifications I'm sure it's violate someone's TOS.
I feel like it would need to work like Opera mini to maybe be usable. Even then interactions would be uncomfortably slow.