Consider adding 'You can also email your query to us at [insert email address here]. These queries will be answered within [insert time frame].' Again, if you intend to make a promise to your customer in a voicemail, ensure you keep it.
A word of warning: These greetings will not do you any favors if you're in the midst of a job hunt or work in a conservative industry. Always remember your target personas. If there's a chance they won't appreciate your sense of humor, opt for a straightforward greeting instead.

Instead of stating the obvious, enhance your message with information your callers can use, such as how to reach someone immediately, when you will be returning calls, or where they can obtain after-hours service. Services that offer multiple custom greetings like Tendant allow you to store multiple greetings so you can have a greeting just for a holiday that you can use every year. Specify the information you want callers to leave. Your voicemail greeting presents a great opportunity to gather important details that will help you better serve your customers. This may include account numbers best times to return the call, and of course, a brief summary of the issue or purpose of the call.
Last, you'll want to take a close look at your current network monitoring tools. At its core, VoIP is simply a specific kind of network traffic, so in the end it'll be these tools that allow you to see that traffic and manage it across your network. Make sure that the tools you're using support VoIP's needs, especially around QoS, traffic analysis, and network congestion issues.