I have Cingular & phone is Nokia 6340I. When another Cingular customer calls & blocks their number, they hear 4 rings & instead of going to voicemail, their call ends. On my end, the phone does not ring, my phone shuts off on their first ring, when their call ends, my phone powers back on. My phone does not show missed call. When a landline or Alltel phone blocks their number, my phone will ring & go to voicemail. Can anyone explain?