Website: https://support.8x8.com/equipment-devices/phones/general-phone-settings/how-to-create-or-change-outgoing-voicemail-message
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.

*Some devices may prompt to allow permissions. These should been enabled to utilize app. Dial *72 and the 10 digit number you want to forward to *727856251234 send you will hear 3 confirmation beeps, end the call. Your phone is now forwarded To turn off call forwarding immediate dial *720 press send, you will hear 3 confirmation beeps. Press end. Your phone is now set back to ring your handset. Dial *73 and the 10 digit number you want to forward to *737856251234 send you will hear 3 confirmation beeps, end the call. Your phone is now forwarded To turn off call forwarding immediate dial *730 press send, you will hear 3 confirmation beeps. Press end. Your phone is now set back to ring your handset. Dial *74 and the 10 digit number you want to forward to *747856251234 send you will hear 3 confirmation beeps, end the call. Your phone is now forwarded To turn off call forwarding immediate dial *740 press send, you will hear 3 confirmation beeps. Press end. Your phone is now set back to ring your handset.
That way you'll get to know exactly what other people hear when they call your phone and one last thing I wanted to show you. If you don't see that play on record option on the bottom, you don't have visual voicemail. Set up on your phone and that's through your provider. So if you have at and T sprint T-Mobile or any other provider, you need to have visual voicemail.