Motorola mobile users hidden tricks...............

  You can change GSM frequencies to 900/1800 by entering the enginnering model.
  Following the below steps:
  enter menu and press 048263* quickly,
  then you will enter the secret engineering menu under "Opcode"
  input 10*0*3 for GSM 900
  10*0*4 for GSM 1800
  10*0*5 for GSM 1900
  10*0*6 for dual band GSM 900/1800
  10*0*7 for dual band GSM 850/1900

  To add extra message space 4 your Motorola C350 C450 C550 or C650,
  press menu button, press 048263* quickly, then on the popup menu enter 47 press ok.
  press 50 and ok.press 1 ok.press 64 ok.press 1 ok.press 186 and ok.
  You will receive an extra 50 msgs memory space.Switch phone off and back on. 
EFR:
###119#1#, (OK) to activate EFR mode
###119#0#, (OK) to deactivate EFR mode

Motorola Code to lock keys. Press together *7 Note: [] (pause) means the * key held in until box appears.

Select phone line - (use this to write things below the provider name):
[] [] [] 0 0 8 [] 1 []

Add phonebook to main menu:
[] [] [] 1 0 5 [] 1 []

Add messages to main menu:
[] [] [] 1 0 7 [] 1 []

Copy SIM memory (phonebook menu):
[] [] [] 1 0 8 [] 1 []

Eng Field options (main menu):
[] [] [] 1 1 3 [] 1 []

Slow (Frequency of search menu):
[] [] [] 1 0 1 [] 1 []

Medium (Frequency of search menu):
[] [] [] 1 0 2 [] 1 []

Fast (Frequency of search menu):
[] [] [] 1 0 3 [] 1 []

Enable EFR:
[] [] [] 1 1 9 [] 1 []

Function :
[] [] [] # # # [] 1 []

Change pin:
[] [] [] 0 0 4 [] 1 []

Unblocking using the "puk" number:
[] [] [] 0 0 5 [] 1 []