We do not sell any modems that provide phone service. However, if you are renting one that has built-in wifi you could trade it in for a stand-alone phone modem that does not have any built-in wireless capabilities and there would not be a rental fee as long as you have phone service. You would then just need to purchase your own wireless router and connect it to the modem.
Cox will freely loan you the eMTA. If Cox issues you a standalone eMTA, you'll need to purchase a DOCSIS. Make sure your choice is on the list of Cox Certified Cable Modems.
If the Solution Store doesn't have a standalone eMTA available, they'll freely loan you a combo device (DOCSIS & eMTA).
A router is your personal network and you can buy whatever you want: wireless, non-wireless, 802.11a, MU-MIMO, 60 GHz, etc. However, Cox would gladly rent you a PoS all-in-one device (DOCSIS, eMTA & WiFi).
Most would recommend purchasing your own router. You only need to determine your needs: your data plan, number of networked devices, ideal location, etc.
UPDATE: Oops...I didn't notice this post is a month old.
That may be true nowadays; however, that's why I qualified a standalone eMTA.
When Cox started pushing their new telephony technology in 2016 (VoIP, Cox Voice, packet switching) I specifically asked the Solution Store for a standalone eMTA because I was happy with my Internet modem. That's what they issued; that's what I connected.
Nowadays, those standalones may be long gone. I don't know.