The telephone systems have the feature named as Voicemail. VoIP is the best example of it. When a receiver is unable to pick up the phone, then the caller can leave the voice message on the receiver’s phone. In older telephonic machines, such messages were stored as a voice message directly, and the receiver can hear them later. In modern telephone systems, such info is being stored on the server of the service provider in the user’s mailbox. It is similar to email in which the messages are saved in the form of audio instead of text.
However, some cellular service providers allow users to access and update their voicemail by calling their own numbers from working landlines or phones on other wireless networks, so users whose accounts include such an option and who have access to alternative service could keep the voicemail greetings updated even when their own mobile phones cannot connect to cellular or internet service.

2. Open the Phone app — the app that you use to make phone calls and track your contacts — and tap "Voicemail" in the bottom-right corner.
2 hours agoFrom another extension in your system: Dial 500 , enter your extension number, then enter your voicemail password, followed by the # key. Press the * key to enter the Main Menu. Note: If you have no saved voicemail messages, you should enter the Main Menu automatically. You can skip this step. Press 2 to change your greeting.