That's not what's advertised at vonage.com under residential plans.

Basic 500 - $17.99
Vonage Pro - $34.99
Vonage World - $25.99 after 6 mo intro rate of $14.99

I will admit the above prices are before all their junk fees are added which adds several dollars/mo. It's unfortunate that a $17.99 plan is really $21.99 + tax. If customers stopped using them, the pricing game would cease.