Best answer: The answers are accurate depending upon what you are looking at. I would like to add to this:
∙ If the question is does this cable modem have built-in VoIP and a port for a phone connection (link you get with some cable providers), the answer is no. This does not have a MTA built-in. Read more below.
∙ If the question is can you have a VoIP provider such as Ooma, Vonage, etc connected, the answer is yes.
This is simply a cable modem that would be able to replace the one that your cable company provides. If the provided modem has a built-in MTA, then you are probably subscribed to the cable providers VoIP service. This is probably costing much more than other services that you could change to. As noted above, you could use an alternate provider such as Ooma (which I have been using since July of 2011), Vonage, or others. Even with the up-front costs, you will save a lot of money over time.
Hope this helps you (although the post was 2 months ago) or others.