@Alok, i am also facing same problem like pramod has mentioned over here. I am using SCH-I509 and initially both networks comes on screen but as i enables data service, it turn to 1x only. 
Please advise how can i get my EVDO activated. 
I placed two requests to Reliance CC and both were reverted as processed but EVDO is not working. They say the request will be processed in 5days but i got Request processed SMS on very next day against both requests. 
Please advise what to do.