Voicemail access and the initial password should have been set by your carrier or service provider when your device was first activated. But keep in mind that some carriers don’t use passwords when it comes to voicemail. If you don’t know if this service is enabled or you forgot the password, you should check in with them first. If you see the contact list opening, tap on the phone dialer icon located in the bottom-right corner.Once you’re in keypad dialer, touch and hold on number 1 key. Now one of two things can happen. One, if you the service is enabled your phone will dial the voicemail number and prompt you to insert or create a new password. You might also be asked to record the greeting message at this stage. And two, in case your carrier didn’t configure this service when your device was first activated, you’ll be prompted with a message to insert your voicemail number. If the first scenario is the case, follow the instructions provided by your carrier to finish setting up your voicemail. In the event that you’re prompted to insert your voicemail number, tap on Add Number. If you don’t know your voicemail number, call your carrier and ask for it or search online for something like “voicemail number + *YourCarrierName* + *YourCountry*”. Now follow the instructions provided by your service provider to finish setting up your voicemail. Note: If you bought a used phone or you recently changed the service provider, chances are you have the wrong voicemail number set up. In cases like this, open up the App drawer and tap on Phone. From there, tap on More and select Settings. Once you’re in Settings, scroll all the way down to Voicemail settings and tap on the entry. This will open a pop-up in which you can change the voicemail number.
You can record custom messages right from your dashboard using Dial-and-Record, which allows you to record it through your phone. Then, once they’ve been recorded, they’re saved in your account to be placed in any section, such as for the welcome greeting, menu prompt, or voicemail greeting, in addition to other sections. Enter the number of rings between 0 and 9, or press #. If you choose 0, calls will go straight to your voicemail without ringing first. If you choose # calls won't go to voicemail at all. The phone will ring until you answer or the caller hangs up. Follow the voice prompts.

Go to your phone Settings and open Cellular option. Now tap on the toggle for Cellular Data option. Turning on the Cellular data; Try using your voicemail and see if the problem still exists. Method 3: Setup Your Visual Voicemail. If you are unable to set up your voicemail through phone settings, then you can try setting it up through your carrier.
You can’t call someone back if you don’t have their number. It seems basic, but it’s easy to forget. So a quick reminder can go a long way.