VoIP packages generally offer the most features at economical pricing, but are subject to the vagaries of your current ISP. You may also be on the hook for purchasing their equipment.
The phone you use to record your greeting – and your surrounding – can turn your carefully scripted greeting into an unprofessional mess. Background noise is terribly distracting, so choose a quiet room or parked car to make your call. Landlines, or a “wi-fi enabled” cellphone call, can provide much better connection quality than a standard cellphone. If you must use a cell phone, be sure to use a high-quality headset for the best clarity.

If all this is starting to sound like more trouble than it's worth, remember that turning your PBX into a software solution means a significant opportunity for flexibility and integration that you simply can't get any other way. After all, programmers can now treat your phone as an app. Where that's taken us is to the fast-changing UCaaS paradigm mentioned above. Here, VoIP providers, like the ones we've reviewed, provide additional software capabilities that are all implemented and managed from a single, unified console.
If you want them to leave a voicemail, tell them right from the beginning, “Please leave your name, reason your calling, and the best way to contact you.” If you want them to call you back during normal business hours, tell them, “Please call back during normal business hours.” If you want them to call back prepared for a lengthy conversation, you can say something like, “Please refer to our website’s FAQ page,” and then provide the URL. Self-service should never be underestimated.