Website: https://blog.toky.co/create-greeting-audios-free-using-text-to-speech-tts-services/
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?

Using the services of a professional actor with experience in phone system recordings helps ensure truly professional-sounding voicemail greetings for a business. Professional actors backed by experienced audio directors and studio-grade recording equipment can produce high-quality recordings for phone system messages such as voicemail greetings.
How to set up your voicemail PIN: After you are enabled for Skype for Business Phone Service, you will receive an email that includes a PIN for your voicemail. Refer to that email, then: Call the Outlook Voice Access number, 785-864-1900 or 4-1900. Enter your temporary voicemail PIN at the prompt.