HOW TO KNOW ORIGINAL PHONE

A quick way to check if a phone is original is by dialling *06# which should display 15 digit IMEI number which is usually begins with 35 followed by 13 other numbers, then compare this to IMEI number under your battery chamber. Both IMEI should be be the same.
Below are unique code for various GSM brands:
NOKIA
IMEI number *#06#
Software version *#92702689#
Enhanced half rate *4720#
Enhance full rate *3370#
Software version *#0000#
To know manufacture date *#0000#
SAMSUNG
IMEI Number *#06#
Sim lock info *0377#
Phone information *0377#
Phone information *#0228#
Battery state *9998*228#
Vibration test *#9987*842#
MOTOROLA
IMEI number *#06#
Net monitor OFF ***113*2*
Net monitor ON ***113*1*
To know manufacturing date dial #         NOTE: Motorolla code is only available for few models
LG, NEC and TRIUM
IMEI Number: *#06#
Software version #6276421#