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.
When you’re using the traditional voicemail system, your carrier dictates some messages you’re going to store in your voicemail box. But with a virtual system, you can store and retrieve messages whenever you want. The cloud also allows you to convert the voicemail audio files and texts and send them via email to relevant departments for further screening.

1. Actually Write a Script! Whether you are a solo therapist recording a voicemail greeting, or you have a whole office and need a system message, don't just wing it!
While missed calls aren’t ideal, you can let your caller know you’re still there for them by having a great voicemail greeting. The best business voicemail greetings let your customers (and potential customers) know why you’re not available and how they can best get in contact with your business. They are also short and to the point. You usually want to keep your greeting between 6 and 24 seconds long so callers don’t hang up halfway through.