Motorola Secret Codes *#06#- Serial No IMEI Menu+# Phone Number Number+#-Speed Dail *#**372# Or *#**376#-Listen FM without earphones There are lots of similar codes exist. If you change the last number to 0 you can deactive that code. The 3 digit number at the middle are from 0 to 999. More codes. (EFR):Enhanced Full Rate Codec. 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.