Read the forum guidelines
Need to switch landline service to Cox. My modem has only one port (ethernet) Do I use a port on the router to plug in the landline phone?
You need a phone modem(eMTA) to use Cox phone service. One is provided as a free lease to you when you start service. The typical model given is the Arris TM3402. It has a phone connection(RJ11) and ethernet(RJ45) for internet. It only provides one ethernet connection, so you need a router for more ethernet and Wifi. If you want wifi built in, you can rent($) a Technicolor CGM4141.
Does Cox give out older eMTA's with lower speed internet plans? I thought Cox was try to inject as much DOCSIS 3.1 into the field as possible?
No I think D3.1 Emta's are standard now
That's what I thought, but I was trying to make sense of Jonathan's post.