A Netopia voice-product registration from the DSL-router era, with nothing public behind it.
IANA lists 1840 (TCP and UDP) as "netopia-vo2", one of a short run of "netopia-vo" assignments made for Netopia, the DSL router and remote-access vendor later absorbed by Motorola and then Arris. No specification was ever published and Netopia's product line is gone, so the registration is a fossil. Nothing in current use binds this port.
Expose with care
The registration explains nothing about a live listener on 1840 — trace it to a process locally before deciding whether it should be reachable at all.
$ nc -vz -w 3 TARGET 1840Seen this on your network? Beige Box scans your Wi-Fi and shows every open port on every device — and its Ports tool links straight back here.
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Corrections or a missing port? Reply @rimrocksystems.