What does it require, if not wires?

And are modern fiber optic cables wires in any sense of the word? Does the relevant statute in USC18 actually define "wire" for the purpose of the crime?

Part of me thinks that wireless communications must be included, but one might make the case that even then, information/communication is transmitted over wire at some point.

Wire, radio, and television. The definition is:

"having devised or intending to devise any scheme or artifice to defraud, or for obtaining money or property by means of false or fraudulent pretenses, representations, or promises, transmits or causes to be transmitted by means of wire, radio, or television communication in interstate or foreign commerce, any writings, signs, signals, pictures, or sounds for the purpose of executing such scheme or artifice"

https://www.law.cornell.edu/uscode/text/18/1343