Prisoners don't have Fourth Amendment privacy protections when it comes to having their phone communications monitored. Prisons can tap and record all inmate calls if they choose, except those between inmate and lawyer. Staffing limitations often prohibit the amount of direct listening that prison authorities can perform, however. Prisons sometimes use voice authentication technology to verify the identity of the person being called. The voice is recorded so it can be matched in subsequent calls the prisoner might make.
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