Are there Federal or state guidelines regarding on call reimbursement?

I am a county employee. (Not Law Enforcement and not a firefighter) If I am required to be on call with a pager and cell phone, ready to respond immediately in uniform in a company vehicle after my normal shift is over, would my employer be required to reimburse me for being on call?

I work four ten hour shifts but I am required to take a one hour lunch each day which gives me thirty six hours a week. During my four days I carry a pager and cell phone and frequently get called out. It is not yet mandatory that I be on call.

It depends on what you mean by immediately. Whether or not an employee has to be paid for being on call depends on how restrictive the requirements are. If by immediately you mean within, say, fifteen minutes, yes, you probably would have to be paid for it. If by immediately you mean more like an hour, then you probably would not have to be paid.

This presumes that you are an hourly paid employee.

With the same presumption, you definitely have to be paid for any time after you're called in. It's only time when you're on call but not working that's questionable.