Yeah, it's not the first time they tried to do something like that. They tried some years ago with pigeons also. And we actually got news from time to time of inmates' girlfriends trying to smuggle cell phones inside, ah, themselves, if you guys understand what I mean.
But there were other news in this last week that is almost better than that. One high security prision got some new and very functional cell phone blockers, that also intercept the calls. They installed it in secrecy, not telling the press or the inmates. In the first days, they intercepted around 30 calls of inmates trying to get in touch to their cell phone companies, trying to understand why their phones weren't working properly
The original link, in portuguese:
http://olhardigital.uol.com.br/produtos/mobilidade/noticias/presos-tentam-reclamar-com-operadoras-sobre-celulares-bloqueados