Context does matter here. If the caller would reasonably expect you to answer the phone (such as if they were calling a store or other place of business), an apology for not being able to get to the phone makes the most sense.
6 Do’s and Don’t’s of writing Voicemail Recording Scripts Follows the do’s and don’t of leaving the correct voicemail for your clients. Write a new voicemail greeting for office following these 6 principles. A lawyer’s office needs to maintain professionalism at all times in order to record the perfect voicemail greeting. Let’s look at an voicemail greetings example.

31. Hi, this is [your name] at [your company]. If you are calling for [include reason] please visit our [website, social media handle, etc.], contact [name and title of colleague and phone number] or send me an email at [insert email address]. For other inquiries, leave a brief message and your name and number and I will call you back by [timeframe].
Customers do not possess the expertise and knowledge you do. When creating your business voicemail greetings, make sure you don’t use such technical terms that the customer may not be able to understand.