How to block SMS on 4G?

Hello Experts.

How to block SMS on 4G? Keep it on 2G / 3G such that if user wants to send SMS, he falls back to 2G / 3G?

How can this be done?

What is the need for CS fallback for SMS?

If you don’t have IMS, you can use SMS over SGs.

We have IMS, but we want to fallback.

Ok, understood.

But I’m curious, is this due to license limit?

It is a test we want to try.

Anyone done this?