A bill now in American Congress called the Safe Prisons Communications Act of 2009 would enable governors or the director of the Federal Bureau of Prisons to petition the Federal Communications Commission for permission to use cell phone jammer in jails.

Prison officials want this passed because prisoners routinely smuggle cell phones into prisons. Last year, prison officials in California alone confiscated 2,800 cell phones.

Incarcerated convicts use cell phones to conduct criminal business and intimidate victims and witnesses

Prisoners use cell phones to bypass the monitored communication systems that prisons use between people on the inside and the outside. They also keep prisoners who have been separated to keep in touch -- gang members and terrorists, for example.

One challenge faced by President Obama in his bid to close the Guantanamo Bay detention facility is that any terrorists transferred to U.S. prisons would have immediate access to cell phones, which they could use to plan additional attacks. So it is necessary to use mobile phone signal jammer in jail.