Last week one day I had a message popup on my iPhone which said my Voicemail password was wrong.  The message caught me off-guard because I wasn’t trying to access my Voicemail and I hadn’t made any changes recently.  Also, I wasn’t sure if it was my voicemail with AT&T or my office voicemail in Cisco’s integrated messaging.  Since I was busy with other things, I didn’t pursue it.

After a couple of days, the message appeared again.  This time I thought I should find out what was happening.

I selected the button (don’t remember the name) to get more details and I learned it was the password with the AT&T.  On my iPhone I went to Settings > Phone > Change Voicemail Password.  There I was prompted to put in my old password (really just a four digit PIN).  I entered the old one which it took (so it means my old password was still valid with AT&T) then entered a new password, which was accepted.  Behind the scenes my phone updated my password.  After exiting Settings, two new voicemail messages appeared. [more]

The gotcha is not new, just surprising in its occurrence.  I had updated my iPhone to iOS 4.x.  I knew the update did not keep up with passwords, but I had reentered email passwords and VPN keys, etc. and everything I could think of at the time.  All appeared to be working.

The Voicemail password error didn’t not appear until a couple of weeks after my iOS update.  The time span was sufficient for me to not realize it was all a part of the update.  The long duration was because I had not received any voicemail.  When I did receive a Voicemail, my iPhone, which after the update did not have any password, tried to authenticate to AT&T and caused the error to appear.

So, after updating to iOS 4.x be prepared for weeks or months of password errors or requests.  Every time you attempt to contact a vendor of an App who had required you to register, you will need to reenter you password.  The message may say the password is wrong, but it really means the password which had been stored on your iPhone has been deleted.  Probably your password is not wrong, just missing.