Found some info for use with page port:

If the V-2006A/V-2006AHF is being used with a page
port, set SW6 Battery Feed to OFF (down position).
Page port must:
1. Provide dry page enable contact closure
2. Pass DTMF tones for zone selection
3. Pass audio in both directions when used with
V-2006AHF for handsfree talkback




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