N6305‘s usermanual第 64 页12.3 Outgoing callsOperations on missed calls.12.4 Call durationThe option call duration can be activated by pressing the key U or D under call record box and pressing thekey select for an access to call duration box. Under this box, following may be viewed: last call duration,total duration for dialed &received calls, total call duration.To clear call duration to zero, just press the key Clear , and confirm with the key OK ; for the same purpose,press the keyCancel to exit from current operation，and a prompt will be given respectively by cell phone.
