The biggest barrier is actually getting them to leave the voicemail in the first place. Don’t get in your own way by recording a long, drawn-out voicemail greeting that might do more to convince them to hang up than actually leave a message.
A general voicemail greeting is what callers will be greeted with if you are unable to answer the phone at work. It is the everyday greeting, used as the default, unless you have set up a temporary greeting, such as an away message while you're on vacation, or a special message during a holiday.

“Hi, you’ve reached [your name] at [your company]. I’m unavailable right now — probably helping [type of company] get [X results, e.g. ‘double their leads in 60 days,’ ‘hire the best and brightest engineers,’ ‘convert 40% more customers.’] Leave your name and number, and we’ll discuss how your company can see similar results.” “Hello, this is [your name] at [company]. Thanks for calling. Please leave your name, number, and reason you’d like to chat, and I’ll get to back to you ASAP.” “Hi, you’ve reached [name] at [company]. If you need a quick response, please shoot me an email at [insert email address] and I’ll be in touch by EOD tomorrow. If it’s not urgent, leave me a message with your name and number. Have a great day.” “Hey, this is [your name]. If you’re calling for [X reason], please [contact so-and-so] or [go to our website, send me an email]. For all other inquiries, leave your name and a brief message and I’ll call you back within [one, two, three] business day[s].” “Hello, you’ve reached [name] at company. I’m unable to come to the phone right now. Leave your name and number, and I’ll return your call as soon as I’m free. Thank you.”
Recognize Their Need. When someone calls your business, the voicemail should give them a sense of validation. This means that your voicemail should extend gratitude for their interest in your business, or an apology for not being there to answer your call. These two simple courtesies can go a long way in the creation or establishment of client/business trust. Make it Informative for the Caller. Your voicemail must include all the information the customer will need for your particular business. For instance, if you’re a brick and mortar establishment, it’s wise to include your store hours. It’s also a good idea to leave them an alternate way to contact you, especially if it’s after hours. After all, you don’t want to miss just one potential customer. Here are some suggestions for elements to include in your voicemail: Business name Hours (if brick and mortar) Alternate method of contact, such as email Your name