Simply speak into your phone or computer while recording a greeting with your business phone service. If you need to create your own audio file, the voice memo app on your phone should do fine.
Website: https://www.mightycall.com/blog/the-best-services-to-record-a-voicemail-greeting-for-business/

These work voicemail greetings are for the work phone that you and only you use. They’re highly effective because they help you establish a relationship straight from the voicemail. Or they help you share an important update in a simple, straightforward way.
Voicemail will give you a brief description of the three steps involved in setting up your mailbox - setting a passcode, recording a greeting for your callers and recording your name. "Enter digits for your passcode." Your security code may not be less than four digits and no more than fifteen digits. For security purposes the system will not accept codes which are consecutive, sequential or your extension. Voicemail will repeat your passcode to you. Remember to keep this passcode secret and to change it regularly. (We recommend monthly.) "Press D" (the 3 key on your dial pad) to discard your greeting and record it again. When you are satisfied with your greeting and have pressed "X" (the 9 key on your dial pad) to save it, you will hear... "Recording complete." Next, you will record your name so that you and your callers hear your name in your voice. When Voicemail says, "Press D" (the 3 key on your dial pad) to discard your name and record it again. Voicemail will close out your session by reviewing your name and passcode. You are now ready to begin using your new Voicemail. ALWAYS PRESS X (the 9 key on your dial pad) TO EXIT THE SYSTEM BEFORE YOU HANG UP!! Questions or problems with voice mail can be directed to JMU Telecommunications at 568.6471. Hours Alerts Seaver Caruso Law Graziadio Business GSEP Public Policy University WaveNet Courses Email Kronos Printing Mail Services Housing Maintenance Request Dining Meal Plans Student Health Center Counseling Center Campus Shuttle International Programs OneStop Academic Advising Student Success Center Writing Center Dean's Office Tech Central for Students Tutorial for Courses Seaver Faculty Association Campus Recreation Housing & Living Community Student Activities Spiritual Life Hub SGA Spring Break Fraternity & Sorority Life Health Center Counseling Center Shuttle Services Academic Calendar Academic Catalog Academic Policies Course Schedules 1L Grade Distribution & Class Ranks Program Learning Outcomes Global Programs Writing Center Law Library Student Administrative Forms Student Accounts Office of Financial Assistance Transcript Requests Career Development Marketing and Communications Faculty Support Services Information Services Around Malibu Student Policies Student Bar Association Student Organizations Student Boards Moot Court Academic Advising Academic Calendar Accreditation and Assessment Career Services Outcomes and Disclosures Part-Time Students Full-Time Students Executive Students Online Program Students Student Clubs and Organizations Housing and Residence Life Campus Recreation Student Employment Student Discounts Career Services Student Success Student Accounts Academic Affairs Enrollment Analytics Administration Marketing Communications Information Technology Dissertation Support Writing Support MFT Practicum Preparation MSBP Practicum Preparation Honor Societies Graduation Libraries Records and Enrollment Parking Information Career Services Financial Aid Student Accounts Student Services Student Employment Faculty Resources Staff Resources Housing for GSEP Students Honor Society Spiritual Life Education Student Groups Psychology Student Groups Pepperdine Apps Academic Calendar Libraries Study Labs Transcripts Public Policy Student Housing Financial Aid Internship Database Search Professional Development University International Travel Policy Career Services Clubs & Organizations Spiritual Life Student Employment Health Center Institutional Review Board Libraries Office of Research and Sponsored Programs Technology and Learning Housing and Residence Life Step Up! Pepperdine Spiritual Life at Pepperdine Hub for Spiritual Life Center for Faith and Learning Business Intelligence Business Services Campus Operations Campus Recreation Counseling Center Digital Signage Health Center Planning, Operations, and Construction Department of Public Safety Student Employment Center for Sustainability Auditing Services Corporate and Foundation Relations Finance General Counsel Human Resources Integrated Marketing Communications Information Technology Department of University Events University Committees