Back when everyone was using ガラケー (garakē, flip phones), calling someone up was known as 直電 (jika-den, direct calling), an act mainly reserved for emergencies and drunken confessions in the middle of the night.
A friend of mine was いい感じになってた (ii kanji ni natteta, on the brink of having a relationship) with a guy we both knew, but after he had the audacity to 告る (kokuru, confess) his love via jika-den, it turned her off completely and they stopped seeing each other. Ah, the complexity of actually calling people on the phone.
Now that スマホ (sumaho, smartphones) have permeated every level of our society, jika-den have been replaced by ナマ電話 (nama-denwa, raw calls). The meaning hasn't changed but the connotations are a little different.