Securus Tech, is the company used for Cook county. Back in 2011 when F got locked up, I had to prepay for my cell and house, it was one account for both. Unlike CPS. I would put money and it was to both accounts. At the time I had comcast for my home phone and earlier this yr I switched to At&T for home and cell numbers. When F violated parole in Aug (this yr) My lines were no longer prepaid and became direct payment (billed to At&T) It was a monthly limit of $75, once its reached u can not receive calls, even if you pay your bill. You have to wait until the next month. If you want a higher limit per month you have to become a prepaid customer. On the house line, I believe it was about $5-6 per call but only 15 min long. For my cell phone it was direct as well. That was $9.99 per phone call 15 min long. My bills are not on the same account so I think that as well had a $75 limit. When I receive my house bill, it was exactly what I thought my bill should have been, I didn't see any hidden costs.
I hope this helps a little. I also don't know when this company will take over, I figure once they do there will be a prompt at the beginning of the call with directions as to how to add money and or set up an account. I am also hoping since I had an account just a few months ago, I may not have to do anything. F will be out Feb and Ill be in Texas so I may not even have to deal with this. Good luck to those of you that have to and If I learn more i will pass along the info.