Are there ready-made solutions for blocking sms by the sender?

Question

Computer networks

Good evening.
Situation:
There are information sms notifications for clients. They are sent from one of the well-known services.
Problem:
Some clients think that if they have any questions (these can be any questions that are not tied to a specific topic), they can safely answer this letter.
Question:
Are there any ready-made solutions so that sending an SMS message from a client back with his questions is blocked and not sent?
(the solution is to write in sms that it is not necessary to answer it, it does not fit, since there are too many characters)
Perhaps there are other solutions to this problem?

Answer 1

Imho if this is really a problem - agree on a letter sender for yourself - SMS will not go to him, respectively, the client will understand that he is doing something wrong ;-)