How do they control cell phone use in prisons?

Factual Questions
1

I was reading an article describing the activities of one Fernandinho Beira-Mar, an imprisoned Brazilian crime kingpin, who was using several cellular phones to manage his business from the pokey.

Now how about that.

Clearly, these must be contraband – they mustn’t let the bad boys call home without being able to listen in – but how is this enforced?

Do they simply toss the cells with extra vigor, looking for cell phones as well as shivs?
Do prison officials use electronic devices to track down cell phone signals?
Do they use jammers?
Are prisoners carrying the smaller models wedged in their backside?

It seems to me that even if the signal was poor within the cells, the enterprising organized crime boss could simply chat in the yard, with a gang of thugs distracting folks.

(btw: I looked and found this thread, but all that was discussed there was that cell phones are verboten).

2

Very surprising.

It isn’t just the phone, you need a charger too (and something to plug it into).

3

From time to time cell phones (appropriate name for them in this context) do turn up on cell searches (spins) and the charger units are also a priority target.

In many jails, there is not the right electricity supply to operate the charger units, though there are ways and means.

More usual is the gathering of intelligence which leads to the discovery of cellphones.

Inmates being the kind of folk they are, cannot help but boast of their exploits, how they’ve managed to get one over the police, or any kind of authority.Sooner or later word gets around, and the likely phone owner is then more closely observed.

Basically, cons hate grasses, but their own gobshite usually is enough, it’s easier to blame someone else for their own downfall.