*#06#: To retrieve your phone’s IMEI code. *#61#: Check if your missed calls are forwarded to a different number. ##61#: To deactivate missed call redirection. *#62#: Check if your calls are redirected when your device is turned off or has no signal. ##62#: Disable call forwarding when your phone is off. *#21#: To check if your calls are being redirected. ##21#: To deactivate unconditional ... More @Wikipedia
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