Type and confirm the following codes in the same way you type in a new phone number.
*3001#12345#* - enter Field mode,
*#06# – show your phone's IMEI number,
*#21# – show settings for transferring phone calls, fax et cetera,
*#30# – show the current status of the presentation of your number while making phone calls,
*#33# – show blocked phone calls,
*#43# – show awaiting calls,
*#61# – show the number to which the calls are transferred to,
*#62# – will show the number to which your calls are transferred to when your phone is either out of reach or turned off,
*#67# – show the number to which your calls are trasferred when your number is busy,
5005# – ishow the IMSI number.