How often can my employer make me be on call? And, do they have to pay me for my on call time?

I work in fire,water, and mold mitigation and remediation as a technician/carpenter in New Jersey. In addition to the regular work week which is most often well over 40 hours my employer has us on call 7 days a week, every other week. In my case the first and third week of every month. I must answer the phone and report to work quickly and in uniform as company policy says a tech must be on site of a new loss in about two hours I do not get paid for any on-call time unless a job comes in. I cannot go to far from home, nor drink any alcohol. The company is extremely undermanned and as result i am often asked to report to jobs after hours even on the weeks I am not on call and does not have enough vehicles which means when I am on call i cannot go directly to a job but must first drive to the office to get whatever vehicle is available. I want to tell them i cant keep being on call every other week because it is negatively affecting my personal life but am afraid of being fired.