Change your iPhone voicemail greeting using the Phone app on your device. The Phone app is the one with the white phone icon in a green box. For many users, this icon is one of the four permanent apps on the bottom of the screen. Tap the Phone app icon to enter the phone application.
3. Enter your Pin Number. You will need to know your pin or passcode in order to check your voicemail. If you don't have this code, you will have to retrieve it from your carrier. You will hear instructions to input your pin. Hit the pound key after you enter your pin. Follow instructions on how to listen to your voicemail. It's usually to push a certain number (like 1). That's all there is to it. You should be able to hear your voicemail messages now.

Select the Voicemail tab. Below "When callers reach my voicemail, play my," select one of the following types of voicemail greetings: System Greeting - Plays a system generated message that utilizes your recorded name and is the default setting for all new users. Personal Greeting - Plays a custom message that you record using a phone.
Step 3. You will be asked to create a voicemail password. Create a password and then tap “Done”