Different required fields for different inquiry types

What I want to do, is to have 1 model inquiry, with different required fields changed by inquiry type, i.e.:

if I want to build a "callback" form with the inquiry model, only 3 fields are required, and if it's a general inquiry all fields are required.

How can I dynamically change the rules function of a model?

define different scenarios…


define different scenarios...

Yeeeeah, great. Thanks a lot!