While email and text support saw an increase in recent years, many customers, partners, and potential hires still prefer to call your company directly. When writing your voicemail script, include basic information such as a short greeting, your company name, an invitation to leave a short message, and the time frame in which the caller can expect a return call. If relevant, you may want to include your office hours, extensions for company departments, and the contact information for your office manager or HR department.
First you need to know how much time your phone system or provider allows for the duration of the greeting. Some are 30 sec some are longer. Then you need to have a few ideas of what you want to say, or ask your callers.

Smith.ai Virtual Receptionists service can answer all your calls, 24/7. We recommend 24/7 answering, as a real person on the line can help you capture and convert more leads and build trust with your existing clients. But if you have decided to limit our services to certain hours, you can upload a custom voicemail message in our system for "after-hours" callers. Here's how:
In Microsoft 365, you can record a greeting, edit call answering rules, set up Outlook Voice Access, edit text message and email notification settings, and turn on voice mail preview using Outlook on the web.