I don't know your router. Try searching for your model number along with QOS in the same search. See if people report good success with QOS on your router.
Also, instead of choosing automatic try setting upstream bandwidth to 120 kbps or some other number as experiments dictate.
Maybe considering to a faster internet from your 200 kbps up that you have now??? Figure about 100 kbps each way to use GV which uses g.711μ. Ianobi's codec suggestion with a SIP provider would be the best if you cannot get better faster internet. It is not free, but it is not expensive.