Website: https://www.jhbtele.com/blog/how-to-record-your-allworx-office-voicemail-greeting-from-any-phone/
4. On Audacity’s main control panel, make sure “Line In” or “Built-In Input” is selected in the drop-down menu for the recording source, marked by a microphone icon. The source you pick should match the port you’re using to connect your iPhone or Android to your computer.

Think through what you are going to say before you place the call. When men hear the beep, they often freeze up and forget what they wanted to say. If you want to be the go-to guy at work, then you have to exhibit competence on all levels. Don’t spoil your confident image by hemming and hawing and filling your messages with “uhhhhs,” and “ummmms.” If it’s a really important call, consider writing out what you want to say beforehand. If the person picks up, great, you now have some notes to remember what you wanted to talk about. If they don’t answer, you can leave a clear and concise message.
You can also upload an unavailable greeting using the OnSIP app. After logging in, click on the Voicemail Settings gear icon at the far right. Make sure that the Custom Greeting is toggled to "on." You will then see an option to upload a .wav file of your choice. This recording will serve as your unavailable message.