iphone 4S and inconsistent voicemail recording and display
I have had my apple iphone 4S for about 1,5 years. People would tell me that they have called and LEFT a message that is they have recorded it. However I would not "see" the said voice mail on the voice mail screen. Since, I would ALSO get some other voicemails I did not worry that much.
I noticed that each time I would have an iOS update, the voicemail would reset and will not take or display voice messages. So after a couple of times, I got in the habit of reconfiguring my voicemail... quite cumbersome since apple updates iOS quite often.
In the past months, despite all this careful reconfiguring of voice mail following iOS update, I have NOT received voicemails that trusted people sworn they left. These messages were important and I did not get them.
So my question is simple: how to set up iphone 4S email to receive ALL voice mails and this, regardless of whether or not iOS has been updated.