If you're a part of the Rebel Alliance and have an unlocked iphone, you may already know that the voicemail button doesn't work. But thanks to some Bothan spies (Gizmodo and iphone Dev Team), you can easily get that button working for any carrier that you're using. You won't get visual voicemail, but at least you'll have voicemail. Check it below:
1. First, take note of what your voicemail number is with your current provider (for example, in Spain the Vodafone voicemail number is 177.)
2. Click on the phone button in your iPhone.
3. Click on the keypad tab.
4. Tap the following code:
The xxx is the voicemail number, in our example it will read: *5005*86*177#
5. Tap call.
6. After a second, the code will have been set.
7. Tap now on the voicemail button and it will automatically call your usual voicemail service.