NORCO (CBS) — More than 700 million people use Facebook – among them are some of California’s most-hardened prisoners.

“For the guys that we catch, it’s one of the most popular things they use in here,” said Sgt. Anthony Roman of the increasing number of inmates getting caught with cells phones.

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Under state law, prisoners are forbidden to use mobile phones.

CBS2’s Jeff Nguyen recently visited the California Rehabilitation Center in Norco and Chino State Prison to see how inmates are accessing the internet and social networking sites from cell phones.

Last year, about 1,500 cell phones were confiscated at the Norco facility.

The California Department of Corrections and Rehabilitation uses a team of Belgian Shepherds to sniff out phones that are smuggled in.

The dogs’ ability to track a cell phone is so keen they’re able to separate a phone from other electronic devices.

“These probably go for about a thousand bucks,” Roman said, as he rummaged through some contraband.

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Authorities say felons are accessing the internet to run organized crime rings, to set up murderous hits and, in the case of sex offenders, to stalk their victims.

“On a couple of occasions we’ve had to talk to a couple of inmates because they have been bothering the victims of the crimes,” Roman said.

Inmates caught with a cell phone could have 90 days added to their sentence.

Some are so bold that they’ve taken pictures of themselves in prison and posted them to Facebook.

CDCR recently reached an agreement with Facebook that makes it easier to shut down pages actively used by inmates.

During one visit, Nguyen saw correctional officers find eight phones at the Norco facility – one of them was tucked in a shoe. It was originally hidden in a deodorant container in an attempt to throw off the dogs’ scent.

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The canines are able to sniff through that. Inmates have tried to mask the scent of their phone with coffee, spices – even peanut butter – but the dogs keep finding their cell phones.