“Hi! You have reached [your business]. All of our staff are currently busy helping other callers. We understand how valuable your time is, and rather than keeping you on hold, we will make sure to call you back.Be sure to leave us a detailed message with your name and number. We will return your call within two business hours. Thanks!”
Hello. You’ve reached the establishment of Binder and Binder Law Offices in West Chapel. We regret we are not here to answer your call. However, your call is important to us, so please leave your contact information and a brief message at the tone, and we’ll get back to you shortly. It’s been a pleasure receiving your call.

iPhone users have another option: You can send a voice message from Apple's Messages by tapping the microphone button inside the text box (this works only when you're messaging other iPhones). By default, these voice messages last for only two minutes before they are deleted, but you can change that. Either tap Keep under any sent voice message or go to Settings > Messages and tap Expire under Audio Messages. You can set the expiration date to Never, but this affects only your record of the conversation, not the recipient's.
You should script out your greetings, rehearse, and find a tone of voice that is reflective of your professionalism and your company’s personality. If applicable, your tone and your message should take into account that certain industries and companies are more conservative than others.