While it is understandable that not everyone likes to use the default voicemail greeting messages on their devices, there is a simple and quick way to alter the voicemail greeting on the Samsung S20 from any carrier (including Verizon, AT&T, T-Mobile, Spring, and others).
From a Home screen, tap the Phone app . Tap Voicemail .Tap the desired message then tap the Trashcan icon . Tap Deleted Messages.Tap Clear All (upper-right) then from the prompt.Tap Clear All to confirm. Select the Voicemail tab. Note: Alternatively, from the phone app, select the Keypad tab > select and hold the 1 key > if prompted, enter your voicemail password > follow the prompts to listen to your messages. Select the Voicemail tab, then select Set Up Now. Note: Alternatively, you can set up voicemail by selecting the Phone app then pressing and holding the 1 key. If prompted, enter your voicemail password, then follow the prompts to set up your voicemail.

4 hours agoVoicemail is an audio or voice message that’s recorded when you’re busy with another call or when a phone call goes unanswered, for you to listen to later. It’s different from the age old answering machines in that instead of storing the message on the device, it stores it in a mailbox on your service provider’s server, the same way an email message is stored.
When you first set up your Android phone, it may ask you to record your greeting for the caller. You can also keep the default greeting stored on the device. But, in future, if you want to customize the Voicemail greeting or want to create a new one, then you may need to delete the old recordings from Android. It may not be necessary depending on the Android device model & version; it’s good to know the process.