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.
Website: http://cdn-media-att.vtp-media.com/ecp/documents/product_Product/224/QuickStartGuide/7116/1070_QSG_i5.pdf

Before you record a professional voicemail greeting, you may want to consider the type of people who might call your home or business. That way, you can think about the information these callers might need before you compose your greeting. Most callers are familiar with how to leave a voice message, so try to avoid giving them instructions. Some things you may want to include in your greeting might be your full name, title, name of your company, and an alternate method of reaching you. If you plan to be unavailable for some time, it can be a good idea to tell your callers when you will return and give them the name and phone number of another individual to call in the event they need immediate assistance. A private voicemail box enables a person to receive telephone messages when the phone cannot be answered.
Website: https://docs.microsoft.com/en-us/skypeforbusiness/deploy/deploy-enterprise-voice/configure-voice-mail-escape#:~:text=To%20configure%20voice%20mail%20escape%201%20Start%20the,can%20range%20from%200%20milliseconds%20to%208000%20milliseconds.