I don't have a wall jack because I've been using Vonage on my cable and I've disconnected my land line. I'm getting blinking red on my tab. Will Ooma work with no land line and a direct connection through the cable modem?
I currently have an Ooma hub connected to the internet without a landline and it works great. I also connected the "Wall" port on the hub to one of my phone jacks so that I could connect any phone to any jack in my home and the hub takes care of the rest. I also use 2 scouts in a couple of bedrooms so they can take advantage of private numbers and voicemail. It all sounds complicated but if you take care when you set it up it's a piece of cake.
All that said, you should be fine with just a direct connection. Before I fully integrated my hub I just had a phone connected to my hub and my hub was connected to my internet modem.