there is no software or hardware unlock for iOS 5 so no question about gevey sim unlock as well .

http://iphonehelp.in/2011/11/02/are-att-sprint-iphone-4s-unlocked-in-us/

they claim it is unlocked here for US as well but i doubt. It will work in Nepal though !

edit : you did not mean 4s (plural right ! no CDMA phone will work in Nepal as Juggy said  ) i was refering to 4S not 4s