Like a few people have mentioned, this is a CDMA exclusive but there are similar phones like Nexus one and Desire with GSM variants. Otherwise you may want to wait if you really want the 4.3" screen. Something is bound to pop up in the coming year.
Well both CDMA and GSM are used in India so in theory the op could switch to a CDMA. Carrier but we all know it would depend on bands and frequencies etc.... They probably use WCDMA ( just a guess and too lazy to look it up actually haha) but to answer the ops question No the Evo is not a World Phone