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.
Make sure to keep your voicemail greeting fresh and new. In fact, updating your voicemail regularly will ensure that people actually listen to your message. Anytime you are on vacation, at a conference or other industry-related event, change your greeting to reflect where you are at.

With German-engineered sound design, the new Snom series is designed to provide the small business market with the best sound quality and make it easier to add new people and integrate employees who use their mobile phone more than their desk phone. The new platform can start with just 2 lines and 2 phones, then easily grow up to 100 lines and up to 300 cordless, desk phones, and smartphone mobile users. And it’s your choice to have your phone services hosted in the cloud or installed to traditional landline phone lines in your closet — whatever makes the best financial sense for your organization right now.
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.