A phone call was a communication made over a telephone.
In 2268, James T. Kirk told Bela Oxmyx to make phone calls to the other Iotian bosses. (TOS: "A Piece of the Action")
In an alternate timeline in 2390, Harry Kim told The Doctor that using the temporal transmitter to communicate with Seven of Nine fifteen years in the past was "no ordinary phone call." (VOY: "Timeless")