rgm12355,
I'm curious why your focus is on what happens after your allowance is depleted rather than on ways to conserve your data so as to get through the entire month?
Using lots of data and having an ISP with data caps do not normally play well together.
There are however a large number of ways in which data can be conserved thereby making it available for other purposes.
Having data caps demands that you run a very tight ship or you will be at the mercy of FAP at every turn.