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The NETGEAR AC1600 WiFi Cable Modem Router does not have a telephone port. Is there any way to hook up telephones to it through an ethernet port?
Why did you choose this modem?
Not through Cox. In order to use Cox telephone service you would have to use the phone modem provided(for free) by Cox. The latest phone modem from Cox is the Arris TM3402. If your looking for a all in one (phone,internet,wifi) then the model is the Technicolor CGM4141. Although in general I suggest using your own router.
Is the OP's modem even certified?
ARRIS Surfboard TG1682: D3.0, 24 × 8, Cox Voice, 300 Mbps/30 Mbps, WiFiARRIS Surfboard TG2472: D3.0, 24 × 8, Cox Voice, 300 Mbps/30 Mbps, WiFi
for free phone service, good luck with that.