|Source: Campaign for Prison Phone Justice|
On the campaign's website, there's a fascinating chart (pdf) created before the FCC ruling showing how widely states vary in prison phone costs. Texas' rates are around the middle of the pack, to the extent it's possible to make apples to apples comparisons. That table had TDCJ receiving a 40% "kickback" on the costs families pay for inmate phone calls. Under the new rules, said the fact sheet, "Costs resulting from kickbacks cannot be passed on to inmates and their families, and are no longer considered part of the cost of providing phone service."
After the FCC ruling, according to this chart (pdf) posted by the campaign, TDCJ rates for a 15-minute call would decline by 32.5%, from $6.45 to $4.35. The old rate for collect calls was $.26 per minute for in-state calls and $.43 for calls out of state, with $2.49 per month tacked on for "billing" costs. (Source.) Grits emailed the TDCJ Public Information Office to ask for the updated rates and will pass them along when I get them.