I myself don't know when 4g will be nationwide but I do know that where I live it may be 6 to 12 months or longer.The price won't change for 4g so no, you won't pay less for 4g even if you are on 3g. Now 3g will operate on the 4g and as Mr. Hesse said, you get more but won't pay more for the 4g. From what I have been reading it actually cost more to operate on the 3g network so as they add cities it will save them money.
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