Recording the message yourself doesn’t mean it can’t be done professionally. You can still get studio time with an experienced audio engineer. Studio time can cost $60-$100 per hour, which may or may not come with an engineer. If you need to hire one, their rates are usually $100-$300 an hour. Mind you, their feedback, professional experience, and editing capabilities are typically well worth the extra expense.
The first time you tap Voicemail, you’re asked to create a voicemail password and record your voicemail greeting.

Website: https://www.sprint.com/en/support/solutions/device/change-your-sprint-personal-voicemail-greeting.html
A good voicemail greeting is short and professional, lets people know that you’ll get back to them, and invites callers to continue engaging with a call-to-action. You should also show your personality if you’re in an industry or role that allows that. If your industry is more conservative, however, you’ll want to keep humor and personal touches to a minimum. A greeting Your name Your company A simple explanation for missing the call (e.g. you’re away from the phone or are on holiday) A rough estimate of when you’ll get back to the person An alternative person to reach out to (if you’re out of office) An alternative mode of communication (if you prefer email or text) A call-to-action such as “Leave a message” or “Send me an email at [email protected]”