Google Voice confusion....

[thegame69]

ok so here is the thing that me as well as others are probably confused about....so here is the thing...im currently using the google voice app and it works fine...so why would i want to use gvdialer instead??? what would be the benifits??? from what i have seen they both do the same thing....right?? also here is another thing...i live in chicago so since im in the U.S does that mean that i wont get charged extra when i call people correct??? so if i wanted unlimited outgoing than do i just add my google number or do i add the number that googles dials when i call someone using google voice???? i saw that some people do both so whats the point of that??? i basically want to make sure i dont get any extra charges...as of right now i only have the number that google uses when it dials out...so is that all i need or do i have to put in my google phone number also???? any help will be appreciated to help me out as well as others...thank u