The federal Fair Debt Collection Practices Act does not limit calls to a specific number per week, nor does it even describe calls about a minor child's debts. There may be state laws that do so, but we aren't attorneys so we can't describe the specific rules in each state.
Can you tell us a little more about this situation? You asked about Mississippi but you are in California, can you explain? What type of debt is this and what's the situation with the debt?