Many callers will be respectful of your wishes and follow your directives. This is extremely vital for reducing your voicemail volume.
Ideally, a business should have a complete set of messages for every phase of their call flow from beginning to end. While voicemail greetings are an important part of the phone system, there need to be recordings for everything leading up to the voicemail as well (assuming there are other steps in the call flow).

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.
You can’t always get to the phone when clients, partners, investors, or colleagues call you. When this happens, a professional voicemail greeting helps you make a positive impression and tells them what to do next. There are a variety of ways to convey your message. If you’re not sure what type of message to record for your own voicemail box, here’s a definitive guide to get you started.