I bought a new iphone 4, and having problems changing my voice mail.

make sure you do not have the settings set to block mode, people often confuse block mode as being the setting that blocks other devices from piggy backing on their wifi. it actually blocks calls. check the top of the phone for the symbols or icons, if you see one that you dont' understand open settings. and make changes.

when you set up voice mail it has you make a password or try the site for where you got your phone. dial your own number takes you to voice mail

This procedure allows your iPhone to ring for longer or shorter periods than the default setting of 20 seconds before voicemail answers. *** Attempt at your own risk but if you pay attention to the keys you input and follow the directions you should have no problems.

1. On your phone, dial *#61# and click Call

The screen will display:

Setting Interrogation Succeeded
Voice Call Forwarding
When Unanswered
Forwards to +1xxxYYYzzzz
Enabled

2. Write down the xxxYYYzzz number (including +1) - this is the number to your voicemail.

3. In order to make the + appear on the keypad in the next step you'll have to hold Zero down for a few seconds, then it will become a Plus (+). Dial **61*+1xxxYYYzzzz**30# and hit Call. +1xxxYYYzzzz is the number you wrote down previously, 30 is the delay in seconds. The delay can be set in 5 second increments, 30 is maximum.

4. Dial *#61# to verify that the new settings are active.

5. Verify working voice mail.

If you find you or your contacts are not being forwarded to your voice mail you have incorrectly altered your voice mail forward number.

To find out what it is and try again:

Dial ##002# and send. This will reset that forward number to factory defaults.

By then Dialing *#61# you will again display the your current (default) voice mail forwarding number.

Return to step [2] and continue.

*** Use this tutorial at your own risk ***...and if you have the time you can always give AT&T a call to have them change the number of rings on an incoming call before Visual Voicemail kicks in. I was able to quickly change the duration on my own, using these diagnostic iPhone GSM codes. The default time duration before Visual Voicemail intercepts the call is set by AT&T to 20 seconds. You will be able to add another 10 seconds yourself, but if you want your callers to wait more than 30 seconds before voicemail picks up then you'll need to contact AT&T technical support - they can change the duration to 45 seconds upon request.

to retrieve deleted voice mail, there is a great iPhone Data Recovery tool for you to have a try! I have used it on my new iPhone 5 for lost files recovery!

Unfortunately, solution is NOT free. Until Apple decides to take good look into this issue, you are left to buying another BT headset model.

I got lucky first time around, bought new Plantronics (not Playtronics...) Voyager 520 (I do love Plantronics 3xx design, this is the next best thing). It did cost almost twice as much as my previous headsets (about 45 EUR), but it's still on the cheap "side" and (to my experience) also the best value.
Hope new headset also lasts almost whole week before needing recharge, like my "old ones". :)

Though iPhone uses quite a different storage mechanism, still you can recover deleted or lost data (such as text messages, voice mail, contacts, photos etc) with a third party specific iPhone data recovery software called Tenorshare iPhone Data Recovery. I used it to recover deleted voice mails from iPhone 4s and it worked.
You can give it a shot! Download it from http://www.any-data-recovery.com/product/iphone-data-recovery.html

Here is a tutorial to guide you recover your voice mails:
How to Recover Deleted Files from iPhone
Good luck!

Frist U Change LCD Second Change Display Strip Third Change LCD IC  In Last Flash Phone.

Settings-phone-Change voice mail password.

it took 2 weeks for AT&T to figure this out. Essentially, you have to be on the Edge network for the Visual Voicemail to work. I was on wi-fi, and was therefore the VM was not working. The easy fix for me: press and hold the home button (round button at bottom) and the power button simultaneously. then slide the bar over that appears on the screen. this will get you back on the Edge network, and problem solved. you will know you are on the Edge when the "E" appears at the top near your service bars. hope this solves your problem.

go into settings - general - reset and then resetting network settings. This should restart your iPhone.

This alone didn't work, but dialling 1760 to switch off voicemail then 1750 to switch it on again. This works!

Silver007