Don I've used it all 100,50,20,10,5,1, the only place i had any trouble changing bills was in a jewelery store in Zhuhai.The only way they would take them was if they all had the same mint mark.
I worked for a landscaping company in 1987.A couple of the company trucks had.Phones in them.They didn't work real well.You would dial the number you wanted to call.And it would connect with a complete stranger on a land line in the next city.Or it would go to the mobile operator.And she would dial the number.And the call would still go to the wrong person.The company pulled the phones out of the trucks after a couple of weeks.And sent the phones back to the guy they had bought them from.
If I remember right.The air time on one of thoose phones was way to expensive to make them practical.