Android phones can access voicemail by holding down the 1 key on the dial pad until the phone dials your 10-digit phone number. You will automatically connect to your mailbox and be prompted to enter your temporary password; this password is the last 4 digits of your phone number followed by the # key. Start the Google Voice app. Tap the three horizontal lines at the top left of the screen (sometimes called a hamburger menu), and then tap “Settings.” In the Voicemail section, tap “Voicemail greeting.” Tap “Record a greeting.” How do I access my voicemail? To call your voicemail on an Android phone, simply open your phone’s dial pad and hold your finger down on the “1” key. You can also call your voicemail from a different phone by calling your own number and tapping the pound key. How do you check your voicemail?
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This solution worked for me: https://www.reddit.com/r/apple/comments/3lm2eh/difficulty_changing_voicemail_gre eting_in_ios_9/cyngnjr
An extended absence greeting lets you record an alternate greeting without deleting your standard or personal greeting. It can be used as an after-hours message or for special instructions. To add an Extended Absence Greeting, first dial into the voicemail system. Either: From your mobile device, dial 1 + your 10-digit cellular number + CALL Or