Once you have your message, you need to actually record it. The exact process varies depending on whether you’re using a cell phone or office phone, but here’s the basic process: Press the voicemail button, or press and hold 1 on most cell phones. Enter your password. Record your message. Listen to the message you just recorded. Follow the prompts to save your message. Following Up on Voicemail Messages
You can delete individual voicemails as you listen to them, and most networks will automatically delete old voicemails after 30 days. However, few networks offer a simple way of deleting multiple voicemail messages when your mailbox is full – unless you can use an option such as Visual Voicemail, which lets you delete messages with a quick tap of your finger.

After that, relaunch the app. This may fix the issue of voicemail not working on your device.
ObjectiveApplies ToProcedureChange Voicemail Settings in Account ManagerAdditional Information ObjectiveApplies ToProcedureChange Voicemail Settings in Account ManagerAdditional Information Please note: there is no default voicemail password. If you have forgotten your password, you can reconfigure it in your 8x8 Work application, or contact your system administrator. Note: Setting up voicemail for a Toll-Free Number or Virtual Number (such as your main company number) simply depends on what extension the number is pointing to. After that is established, you can proceed to set up voicemail for that extension using the steps provided below.