Most voicemail systems include both capabilities and require a physical connection to your phone system. However, just because they have both doesn't mean both have to be utilized. Some businesses like voicemail, but not automated attendant. Some only want automated attendant at night when no one is available to take calls. Most systems are pretty flexible and can be tailored to just about any business.
Some quick points highlight the benefits of the technology.
On average, it takes three attempts to finally reach someone on the phone. The average length of a business phone call is five to seven minutes. The average voice mail message is less than thirty seconds. Consider that most phone calls are less important than the work they interrupt. One out of five written messages are either lost, temporarily misplaced or written incorrectly.