I'm not going to waste anyones time with whether or not Corrections needs this technology. What I am going to point out is that California is flouting Federal law by employing these jammers. And before I get another "it's for the children/public safety/peace in our time" hogwash, it is against Federal law to employ ANY sort of jamming, except, and I'm quoting from the FCC whitepaper, "There is a very narrow exception. In limited circumstances, the sale of signal jammers for use by authorized federal agencies may be permitted. See 47 U.S.C. § 302a(c); 47 C.F.R. § 2.807(d)."
California/WTFever Corrections is not Federal, therefore, illegal in this context.
EDIT: After a bit more poking around, it seems Global Tel is operating some sort of rogue BTS, and not just blindly jamming, so my bad. However, this introduces a host of licensing/operational issues. I don't GSM/LTE much, so I could care less, but this strikes me as a bad idea all around.