Problem Summary. I have two Sanyo cell phones with Sprint PCS service. Recently, the envelope icon stopped showing up when new voice mail messages had been received but not listened to. So, I didn’t know there were new messages. The problem seemed to occur after an evening when the phone was losing and then regaining signal. So, for an entire day, while the cell phone was in a very high quality signal area, the phone would ring, but no notification icon would appear for new messages.
Problem Solution. For this particular phone, a reset code of ##658032# will initiate MDN Service Programming. However, this doesn’t work for all phones. By entering this mode, choosing Edit, and pressing Okay twice, the phone can be reset. What seemed to fix the problem was turning off the phone, removing the battery, waiting one minute, and then inserting the battery again and powering the phone on.
Problem Avoidance. When in areas that offer a very weak signal, depending on the phone, the service connection may come and go even when the phone is stationary and sitting on a counter. It is suspected that this causes problems with the central tower. After an extended period of time, it is suspected that the central tower could interpret this as a defective phone. It may be best to simply turn the phone off if the signal is not sufficient to maintain reliable service. However, caller ID will no longer work.