I've linked to it elsewhere in this thread (as a response to someone who appears to be ignorant that prison services are an industry), but here's a YC announcement for Pigeon.ly, a YC15 batch that "is building a profitable new category of services for the 20M ppl with family in prison":

https://blog.ycombinator.com/pigeon-dot-ly-yc-w15-a-startup-...

https://techcrunch.com/2015/03/24/pigeon-ly/

Pigeon.ly's creator is an ex-convict who served 4 years of prison time for marijuana business. His first-hand experiences with the cost of telecommunication services is apparently what sparked his startup idea:

> One of these ideas was a way to make prison calls cheaper. There are only a couple of companies that handle the vast majority of communications in and out of prisons because messages and letters need to be carefully screened. Because of this market concentration among players like Securus and JPay, it means that prisoners — who are already vulnerable and often lower-income — get gouged.

> Three hundred minutes can cost $70.

> “While I was there, my eyes really started opening up. I started noticing how grossly inefficient everything was,” he said. “I thought, I know I can solve this problem. This is a real market.”