Your business depends on customer engagement, and voicemail messages are a large part of that engagement. A voicemail is nothing more than a digital recording system, where messages are stored for you to retrieve later. Voicemail allows you to be able to connect with customers while you are away or during your off-hours, where they can drop off a message while you are gone. A voicemail greeting, on the other hand, refers to the message that your callers hear upon answering the phone.
But it can also handle other functions, including session setup (initiating a call at the target endpoint—the phone you're calling), presence management (giving an indicator of whether a user is "available," "away," etc.), location management (target registration), call monitoring, and more. Despite all that capability, SIP is simple compared to other VoIP protocols primarily because it's text-based and built on an easy request/response model that's similar in many ways to both HTTP and SMTP. Yet, it's still capable of handling the most complex operations performed by business-grade PBXes.

Website: https://www.snaprecordings.com/blog/preparing-your-business-messaging-for-covid-19-impact
When making an investment in a new phone system that needs to integrate with other systems, the Switchvox system makes the most sense. Regardless of how your business changes and grows, your initial investment is always protected. Using standard IVR/XML scripting, you can easily connect your database and create steps to take your caller almost any direction you can dream without having to know anything about phones or phone system software! For example, a school might offer parents a custom absentee line to quickly report student absences or a company may route new callers to sales people but existing clients are routed directly to a customer success team automatically based only on the Caller ID.