some points to be considered .. in general while buying 2ndhand phones
>if 2ndhand phone is too cheap .. then there is something fishy
>check out keypad
>phone signals(infact 50% of 2ndhnd's have this problem)
>screen flickering???
>chck out imei no. on bac side with phone i.e type in*#06*
and compare it with imei on back side below battry
>speakers ,bluetooth
>finally battery