The telephone ringtone for my IPhone 5 suddenly started ringing (usually 2 rings) without a call. Nothing pops up and there is no record of a call. I reset the phone twice to no avail and changed ring tones several times. But whatever ringtone I set it uses the "Old Phone" classic tone. Only solution has been to turn off the ringer and let it vibrate. Do not want to do a reset to factory defaults if it can be avoided. My carrier is ATT. Any help would be much appreciated.