BTW The Touch-Tone (aka DTMF) _standard_ specifies a grid of four "low" tones, and four "high" tones.
AUTOVON phones WERE 'standard' in that they used the frequencies that were in the specification and *only* those things that were in the standard.
They were 'unusual' in that they used *all* the dual-tone pairs specified in the standard. There was nothing not compliant with the standard about them.
If you want to get technical about it, the 12 button (and 10 button) phones are, strictly speaking, "subset implementations" of the full standard.
The fact that subset implementations are more frequently encountered than the full implementation is irrelevant to the fact that the full implementation *is* a standard implementation.
Which proves that that facility was not AUTOVON-enabled, since MLPP (via the 4th-column touch-tones) was part of the design spec. of AUTOVON, from "day one".
This was possibly the Army's SCAN. predecessor to AUTOVON.
Or maybe "limited functionality" tie lines to a 'real' AUTOVON facility.
The features and capabilities of AUTOVON, as of its activation in late
1963, are well documented in the literature. Specifically including 'command and control' capabilities using (DTMF-based) MLPP classification of calls, automatic call pre-emption based on that 'priority', and DID/DOD.OK, that clarifies things. That base was *not* on AUTOVON, nor it's predecessor SCAN. They had _limited-functionality_ tie-lines to a SCAN or AUTOVON facility.