Still no SMS, or am I missing it
Resurrecting an old thread to ask if a possible "solution" might be something analogous to the old analog pre-recorded message "The number you have reached ... has been disconnected." That is to say that if no digital interface exists to support SMS transmission, why not bounce the text back to the sender with a preface stating that SMS to this number is not supported? I gather that SMS protocol, when initially designed, just didn't consider this; otherwise, it would have been done already if there was a perceived need and such a solution were both possible and cost-effective.
Re: Still no SMS, or am I missing it
That's really a question for cellular service providers. They are discarding undeliverable SMS messages within their own networks. If they want to let their customers know when that happens, then they're free to do so. Landline providers are not in a position to know anything about that.