A Handbook for Inmates in Eastern State Penitentiary (Philadelphia, PA) in the 1960s describes the Penitentiary’s communication policies at that time.

Personal Visits

The holder of an annual visiting pass for a particular inmate was limited to two visits per month with an interval of at least 15 days between visits. Allowed visiting time averaged one-half hour. Inmates could also secure a special visiting pass through an explicit request to the Director of Social Service. The inmate was then required to mail the special pass to the visitor prior to the visit. Special-visit passes were limited to a maximum of one per month. A group of up to three persons would visit an inmate on a single annual or special-visit pass.

Letters

Inmates were allowed to mail one letter per day that the Penitentiary mail room was open. Letters could only be addressed to persons on approved correspondence list. Letters strictly pertaining to the legal matters of the inmates case were not restricted in number. Pennsylvania paid for the postage of mailing one letter per week. Letters were limited to one sheet of paper. The number of letters that could be received was not limited.

Other communication media

Inmates had access to a library within the Penitentiary and newspapers. Inmates also had access to radio and TV. Movies were shown weekly.