If your job involves a lot of talking on the phone, take the time to learn the NATO phonetic alphabet. "If you need to spell something out, you'll always have a way to clarify which letter you've said without having to think about it, and it sounds more professional than, 'B as in boy, L as in...uhhh...Larry.'"
Your voicemail needs to have relevant information such as your name, who the prospects are connecting to, the department you work in, why your not available to assist your prospects, when you will call them and related information, this is what the prospects would prefer hearing instead of dragging the voicemail messages speaking about your brand and more.

I’m going to ask you to consider something you probably have never given much thought to: your own voicemail greeting. You may call this your outbound greeting or outgoing message. No matter what you call it, this is what callers hear when you don’t answer your phone. Or should I say, it’s what callers are forced to listen to even though they don’t want to.
Users often don’t invest enough time into their messages, resulting in incomplete, unprofessional, or otherwise under-whelming greetings. Sure, crafting a greeting doesn’t sound all that complicated; however, there are a number of pitfalls users can fall into—i.e. informality, terseness, sincerity, lack of direction, and more. While none of these sound too catastrophic, they are often interrelated. As such, they tend to worsen any problem. For example, humor can cause informality, worsen ambiguity, and weaken sincerity. That being said, users should strive to avoid ALL these pitfalls.