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Would it be possible to use an ethernet based telephone VoIP adapter with Cox Voice? Or do you need to use a coax phone modem? If the phone modem is required and I buy a docsys 3.1 from the cox certified list, will Cox be willing to activate it for voice?
Just to focus in on what Darkatt said, you can't buy your own voice modem (eMTA) with Cox. They provide you one as a free lease and uses coax. The latest one is the TM3402. FYI you can use a virtual client with their Cox Business Voicemanager, but that is probably beyond what you are trying to do.