At something like a cent per message, both ways, SMS is annoyingly expensive for any application with a lot of back and forth traffic - hence, chatbot-over-SMS

At something like a cent per message, both ways, SMS is annoyingly expensive for any application with a lot of back and forth traffic - hence, chatbot-over-SMS solutions are rare, and auth providers charge extra for SMS based verifications. Does this create a niche opportunity for dumbphones where in-network SMS is cheaper to provide a light-llm-over-ssm service?