The earliest documented commercial 9600 bps voiceband modem was Codex Corporation's QAM-based product (October 1971), credited by Codex's own John Pugh — not to Lucky or Bell Labs

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James L. Pelkey's History of Computer Communications — built from the Pelkey Oral History Collection at the Computer History Museum, and the basis for his ACM Books title Circuits, Packets & Protocols — records that "in October [1971], just after the close of the fiscal year, Codex introduced the QAM-based 9600, the long awaited successor to the AE-96, priced at $11,500." The page quotes Codex's John Pugh directly crediting the product to Codex's shift to quadrature amplitude modulation (QAM): "we had then announced our 9600, which was a QAM machine. We had the market all to ourselves for several years because it took [AT&T and Milgo] that long to catch up."

This account attributes the first commercial 9600 bps product to Codex, not to a direct line from Lucky's 1965 Bell Labs paper — the page never mentions Lucky, Bell Labs, or adaptive equalization by name, though QAM demodulation at higher constellation densities is inseparable in general engineering terms from adaptive equalization to correct intersymbol interference (claim-lucky-1965-adaptive-equalizer-steepest-descent-transversal-filter). The five-to-six-year gap between Lucky's 1965 paper and Codex's October 1971 product, plus the different company and modulation scheme, complicate a simple "Lucky's equalizer → commercial 9600 bps" causal chain: the popular one-sentence version of that story appears to compress Lucky's enabling technique, a half-decade of subsequent engineering, and other firms' modulation innovations into a single attribution. See claim-lucky-9600bps-attribution-traces-to-unsigned-ieee-comsoc-timeline for that popular version's actual (weak) source, and question-verify-lucky-equalizer-enabled-9600-bps for the still-open question of whether any primary source connects the two directly.