The next step is very important and you need to get it right. Say your phone number two times very slowly so the person has enough time to write down your number as they are listening to your message the first time.
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.

Voicemail greetings are often a client's first interaction with your business, so its crucial you put time into this to convey a clear and accurate message while also putting across a positive first impression. Having a professional voicemail greeting may be the difference between a new opportunity and a missed caller.
The most important aspect of a voicemail message is that the listener must be able to understand your message. Don’t mumble your words and be sure to speak loudly and clearly. Speaking softly will make it difficult to understand you and may result in the listener not being able to call you back.