V3xx...need some help

Go into your "dialer" app (icon of phone handset, typically green in color). Look at tabs across top of app, select keypad.

Do backup your data and do a factory reset going to settings . That should fix it .

To access your Voicemail please follow these directions. This will get you to your message and provide you easy access to it in the future.

Instructions

• Start at your home screen, tap the square with four little squares inside,
• Scroll left or right through the appliactions and find one that says "Voicemail" (it should look like a green talk/speech bubble with a phone in it).
  
• Press and hold the icon for Voicemail, drag the icon to the location you want. You can move an application icon to another main menu screen. You can also move most-used applications next to Home. And then press save!*
• Tap the Voicemail icon and your message will be on the top screen.

Now you should be able to check your Voicemail at any time and know how to place an icon for convenience.

Hope this helped!
*Information found at:
Manual
Samsung website for visuals and specifications

If it is a voicemail, got to Menu, Voicemail, call - listen to voicemail, or simply press seven (7) to delete it. The icon on the screen may take a few seconds (up to a minute or longer) to go away. If not, go back into menu, voicemail, and look for the option to clear the notification. Otherwise, powerdown the phone and power back up.
Please let me know if you need further assistance.
carsandcomps,
Guru, Premium Expert, Phone Support @ Fixya.com

name and centre no,./ this phone # is provided by your cell phone provider, call and ask for your voicemail box #. they will help you set up. call from land line so you can enter info as provided once this is programmed when you press it it will call your voicemail

call your cell phone provider. This has happened to me before and they can reset it for you.

This happens to me A LOT. It seems to help to delete voicemail messages when I have more than 3 signal bars. To get rid of the Icon you have to leave a voicemail on your phone, use someone elses phone and just leave a message, it should vibrate like it has a new voicemail but the count shouldn't go up, then just delete the message when you have close to full bars.
Goodluck!

call your phone from another phone and leave yourself a new message, then go in and delete that message, it worked for me

You will have to call your voicemail number (network specific) and delete voicemails from there, not from your phone.

Have you tried going to messages, voicemail, and then pressing "clear" or "clear counter"? i don't know what phone you have so i'm not sure if you have that option...