So if consulting firm A talks to consultant B about an engagement, and then decides to go with consultant C because he’s cheaper it’s totally understandable.
If consultant C then calls consultant B for help with that engagement, consulting firm A should expect to get a bill for the time.
I mean first off, its rude.
Secondly, none of us work for free.
Now I’m glad to help when i can, but when it goes from “i’ve got a few questions” to “give me the step-by-step on how to do this” I have to draw the line.