QoS for Vonage and P2P in Thibor 14.

Upstream Bandwidth:  Test your Upstream Bandwidth using any valid testing tool (with QoS turned OFF on your router), then confirm that the "Auto" setting is close to your tested upstream.  If it is not, change the setting to Manual and set the number to about 90% of your tested upstream bandwidth.
Thibor QoS Screenshot

Device Priority:  Enter your Vonage MAC address and set the priority to HIGHEST.

Thibor QoS Screenshot

Ehternet Port Priority:  I disabled Flow Control on mine, it seemed to make QoS work better.  Your mileage may vary.
Thibor QoS Screenshot

Application Priority:  Not a lot to do here.  If you have certain services you want to prioritize, set them here.  I'd set DNS to High, since it doesn't take a lot of bandwidth.  If you have performance problems with other services, set them to Medium or High.
Thibor QoS Screenshot

P2P QoS:  P2P should always be set to Low.
Thibor QoS Screenshot