A steady, featureless hum at 350 and 440 hertz, the dial tone announced, for most of the twentieth century, that a line was open and waiting. Lift the receiver, and there it was: patient, uninflected, entirely without opinion about what you might say next. It asked nothing and promised everything, a connection to anyone, anywhere, provided you knew the numbers.
It is heard now mostly by accident, an old landline in a grandparent's house, a fax machine still plugged in for reasons no one remembers, a prop in a film set in an unspecified past. Its absence from daily life is rarely mourned directly, but something in its steadiness is missed obliquely, the way one misses a room's particular quiet after moving. The dial tone never once told you good news or bad. It simply confirmed that the world, on the other end, was still there.