The Proto-Ionians are the hypothetical earliest speakers of the Ionic dialects of Ancient Greek, chiefly in the works of Jean Faucounau.
[1] The "Proto-Ionians" first appear in the work of Ernst Curtius (1887), who believed that the Attic-Ionic dialect group was due to an "Ionicization" of Attica by immigration from Ionia in historical times.
In his view, the first Greek settlers in their historical territory were the (Pelasgic) "proto-Ionians", who were separated around 3000 BC from both the proto-Dorians and the proto-Mycenaeans.
Faucounau traces this three-wave model to similar views put forward by Paul Kretschmer in the 1890s and the 1900s (i.e., before the decipherment of Linear B), with a modification: the (proto-Ionic) First wave came by sea, the "Proto-Ionians" settling first in the Cycladic Islands, then in Euboea and Attica.
For example, the Treaty of Alaksandu between Wilusa and the Hittite empire bore a Greek name at a time when there was no Mycenaean pottery at Troy.
Faucounau considers that all these arguments are an indirect confirmation of his own decipherment claim of the Phaistos Disk as proto-Ionic.
Faucounau's "Proto-Ionic Disk Language" has most of the properties of Homeric Greek, including loss of labiovelars and even of digamma (both are preserved intact in the Mycenaean of the 14th century BC).
Digamma, in Faucounau's reading of the Phaistos Disk, has in some instances passed to y, a sound shift not known from any other Greek dialect, but suspected in Ionic (e.g. Ion.
Yves Duhoux expresses his disbelief in the decipherment, but does not mention the wider theory, except to deny that the Disc came from Syros.