The reason why you cannot reply to these messages is because these are messages initiated by a telemarketer , like Kaleyra, or an operator partner, for a customer, and these are usually informational or promotional messages. It is not from a phone or a mobile number that has the capacity of accepting any form of response for the messages sent out.

The sender ID would be alphanumeric in nature. If it's for informational or transactional purposes, then this usually is alpha sender ID or header. If it's promotional in nature, then most likely, the sender ID is numeric.