I had the same thing happen to me -- I had been on call from 7 AM til 11 PM 7 days a week at my job, switched to a job where I would not be on call at all... and then learned that I would be on call 24/7. I would get calls at 2 and 3 AM.

I hope you can set some boundaries around the hours you will work or that you find a new job. Don't let it get to you-- these are just plans, not actualities. A lot of sales people talk big.