Good luck. My wife works with 7 other women doing the same job with different personnel in her company. She found out there is a 30k pay difference among them with no justification for such. She's on the bottom, has more education, more experience, and longer time with the company than all but two of them. She was also told she was hired under the wrong salary pay and after 2 years of hearing that, nothing has changed.
And for those telling you that you could be fired for discussing salary is not true. No company can fire you for discussing your salary with others. That's a scare tactic management uses and is illegal. What you make is your business and you can tell who you want. If you work in the public sector in my state, your salary is publish on the internet every year by the state.
Yes. This is true.
What possible reason could there be for this and how do "they" know how much money everybody makes?