Originally scheduled to air on November 22, 1963, it was preempted by John F. Kennedy's assassination. In the alternate timeline featured in The Twilight Zone: Profile in Silver/Button, Button (1986) in which JFK's assassination was prevented, a CBS television announcement is heard: "We will now return to our regular programming" and the theme of The Twilight Zone (1959) is played, a reference to the intended broadcast date of this episode.
Gladys' telephone is a Western Electric Model 202, which was in production when she had her life-altering accident in 1932. Although the phone itself appears to ring, the ringer was housed in a separate "subscriber set."
The trivia item below may give away important plot points.
The original Richard Matheson story "Long Distance Call" doesn't contain the detail about the telephone line resting on the grave of Miss Elva's fiancé. It moves from the telephone operator telling Elva that the downed line is at the cemetery at the edge of town, to the final phone call. After the operator reads Miss Elva's address over the phone, the next call she receives that evening says "Hello....Miss Elva....I'll...be...right...over..."