said by nmbdude :
And, you can achieve the same level of service by using a high quality QoS implementation on a router directly behind your cablemodem - eg using pfSense, and prioritizing your VOIP packets accordingly.
I routinely max out my cablemodem for both uploads and downloads, without any interference to my VOIP.
wtf are you talking about? the OP is talking about cdv....not tradional voip like vonage...