For most phones, voicemail is saved on the carrier's system. When a call is placed to your phone and doesn't go through, the call is forwarded to a voicemail access number that records the caller's message. Some users find voicemail inconvenient, or don't even check their messages. While the iPhone has voicemail service that can be disabled by dialling a number, other phones require the voicemail to be disabled by customer care.
Call your carrier by dialling 611 from your phone, or by dialling the carrier's toll-free customer-care number. You can find the number on your bill or on the carrier's website.
Follow the prompts to speak with a customer-care agent.
Confirm your account by providing the password or the last four digits of your social security number.
Advise the representative you would like to remove the voicemail service.
Make a test call to the phone to make sure voicemail doesn't pick up.
You can dial "#004#" to temporarily disable voicemail on an iPhone -- and dial "*004#" to re-enable it.