Criminals usually tend to use cellphones in order to run criminal organizations, intimidate witnesses and organize attacks on guards, even planning their escape.

"There are pay phones available on the yards, but if you were to go to them now, there's no one using them," said Dana Simas, a spokeswoman from the Department of Corrections and Rehabilitation. "They're empty and a couple of years ago there were lines hours long." she said.

Global Tel expects to have the blocking technology running at the California State Prison in Solano by the end of the year and at all prisons within three years.

Global Tel expects to have the blocking technology running at the California State Prison in Solano by the end of the year and at all prisons within three years.

Last year, California prison guards confiscated nearly 11,000 contraband phones, a sharp increase from 2007 when only 1,400 were found. Even Charles Manson, arguably the state's most notorious inmate, has twice been caught with contraband phones.

Prison officials in some instances have deployed cell phone-sniffing dogs to search for the devices.

New legislation last year made it a misdemeanor to smuggle a cell phone into a prison, punishable by a fine of up to $5,000.

Such actions and technologies should be introduced in worldwide prisons in order to reduce the criminal activities that take place because of inmates calling from within the limits of different prisons.