Why not just use SMS messages? No feeds, literally all phones support them, with MMS you also get photos and stuff... you don't need another party involved for the messages to work, and you're already paying for them.
2. SMS is probably the most insecure protocol created for anything, ever.
3. The experience is as close to as shit as it can get.
4. Most modern messaging features aren't supported.
5. Most devices don't support SMS.
6. You can't sync SMS across devices.