Select Phone.Select Voicemail.Select Call Voicemail.Calling Voicemail. If your voicemail is calling like on this screen, your phone is set up correctly. If not, follow the next few steps.Select Keypad.Enter the Voicemail number and select Call. **004*#Select Dismiss.
9. Make sure Call Forwarding is off. If you have a call forwarding set up, it is likely to cause conflicts with voicemail. To turn off Call Forwarding or make sure it is not enabled

Pro tip: You can double-check to see if voicemail is set up on your iPhone by dialing and calling your own phone number in the Keypad of the Phone app, or by calling your iPhone using another phone.
Open the Phone app . Press and hold “1” to call your voicemail. Enter your PIN and press “#”. Press “*” for the menu. Press “4” to change settings. Press “1” to change your greeting. Follow the recorded instructions. How do I change my voicemail message? From the Home screen, tap the Phone icon . Tap Voicemail then tap Greeting (upper-left). Greeting is located in the top-left corner of screen. Tap Custom to record a greeting. Enabled when a checkmark is present. Tap Record to begin recording the custom greeting message. Tap Stop to end recording then tap Save. Call *86 (*VM) from the handset or the 10-digit mobile number from another phone. Follow the instructions for choosing the language options then press the # key to confirm the choice. When prompted, enter the 4-7digit password then press the # key. When prompted, say the signature (or name) then press the # key. Open your Android’s Phone app. It usually looks like a phone receiver at the bottom of the home screen. Press and hold the 1 key on the keypad. Tap Add number. Tap Service. Tap My carrier. Tap Setup. Tap Voicemail number. Type your mobile phone number and tap OK.