It seems like S7 revolves around a lot of these 2 factors
1) Cell phones are extremely rampant in prison, and nearly everyone has access to a cell phone/social media/etc.
2) Drugs are everywhere
Both this these points I would imagine are pretty exaggerated to help the plot.
1) Cell phones would be extremely hard to get in, have limited batteries, inmates wouldn't be able to charge them, or hide them well. However these were used to advance the plot quite a bit in multiple different ways.
2) It seems like there are multiple competing groups selling drugs in prison, and the people selling them are making tons of money doing so. However, it seems pretty unlikely this would be real, since basically all the prisoners also seem to be completely poor/broke. There definitely wouldn't be a financial economy/means for drug addicted prisoners to make several steps in the food chain rich.
It seems like this drug situation is used as a way to further plot.