Once considered informal when used to mean "a telegram" or "to telegraph," wire is now standard usage in these senses. These are hackneyed expressions involving wire: "under the wire" ("within limits," "by a deadline"),"pull wires" ("to use connections or associations to advantage"),"on the wire" ("on the telephone"), and "lay wires for" ("to make preparations").
Dictionary of problem words and expressions. Harry Shaw. 1975.