A quick web search reveals a number of business options for transcribing voicemail message audio into a text format. Many service providers offer such transcription capability as part of the overall phone service plans they sell, allowing their business customers to have company-wide access to text-based voicemail without being forced to seek a third party for that functionality.
We actually know a top insurance sales guy who did a sales motivational message every day just like this, and people used to call just to listen to his thoughts.

For one, be sure to understand QoS (mentioned above). This means going beyond understanding the concept and moving to how the networking equipment in your office -- or your employees' home offices if you're still at that stage -- can actually implement QoS. Most business-grade networking hardware will be able to handle QoS in more than one way, so testing which method will handle voice traffic more smoothly in your environment is important.
Generally, people that call and leave messages are more likely to be ideal customers of your business. Your voicemail message is often not much more than a formality to the person calling.