2. “Hi! We’re glad you called [company name]. We’re happy to help but we are either on the line with another client or on the go! Please let us know your name, number, and reason for your call today. As soon as we become available, we will call you right back. Thanks!” Ask your callers to leave a short message so you can determine when to return their call.
We’ve heard frightening stories of people who have been hit by huge bills because of annoying marketing calls that went to voicemail, so that's something you really need to avoid, such as this article in the Telegraph.

"I have an at&t iPhone 6s running iOS 13.3.1. Whenever I turn on Wi-Fi networks or make a call or turn off cellular data,my iPhone keeps asking me for my voicemail password.I remember making one but when I try the password it doesn’t work."
From the My Phone Service page, scroll to My voicemail and select Set up voicemail. Choose your voicemail box type. Select Advanced voicemail (suggested method), and then select Next. Subaccounts voicemail access and phone number assignment. Add name and assign each phone number a name to easily identify who is using the line. Select Continue.