Manson was one of a growing number of prisoners who have used phones smuggled into a California institution for unmonitored contacts with the outside world, the Los Angeles Times reported Thursday.
"It's troubling that he had a cellphone since he's a person who got other people to murder on his behalf," Terry Thornton, a spokeswoman for the California Department of Corrections, told the Times.
To thwart the problem, California may turn to so-called managed access technology, which blocks calls and text messages from cellphones that are not authorized. The system is being supplied at no charge to a company that handles collect calls made by prisoners and will be tested next year.
Thornton said it was not known who Manson contacted by phone last year; however, the Times said the syndicated television show "Inside Edition" has aired a clip from a recorded call said to be the infamous cult leader.
"I've seen the world spinning on fire, I've danced and sang in the devil's choir," the caller said.