So I was told that the meps don't use the milper message for in/out calls but they they have their own system, how true it that? If so, how?

In/Out calls are for Active Duty reclass. USAREC has their own system. Also, In/Out calls aren’t for picking an MOS, they are for determining who can reclass. Being an under strength MOS doesn’t mean their is a class seat. MEPS will offer you jobs based on what classes have empty seats available

In and out calls are based on MOS strength and paving the way to either get the MOS to strength. In and out calls are not used by MEPS because you are entering active duty and sometimes the jobs listed on the IN/OUT calls don't line up with available training dates.

So you separated and are trying to reenlist and pick a new MOS? Prior Service Business Rules will give you a narrow range for MOSs to choose from based on what you qualified for. You are coming back in, that is what is different.